glados.no/_files/sound/bss/london/manual/MAIN/Third-party Control Protoco...

1152 lines
54 KiB
HTML

<!doctype HTML public "-//W3C//DTD HTML 4.0 Frameset//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta name="generator" content="Adobe RoboHelp 9">
<title>Third-party Control Protocol</title>
<link rel="StyleSheet" href="HtmlHelp.css" type="text/css">
<style title="hcp" type="text/css">
<!--
span.hcp1 { font-weight:bold; }
table.hcp2 { margin-top:14pt; }
td.hcp3 { vertical-align:TOP;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
p.hcp4 { text-align:center;
margin-bottom:0; }
img.hcp5 { border-width:2px;
border-style:solid;
margin-top:0px;
margin-bottom:0px;
margin-left:0px;
margin-right:0px; }
td.hcp6 { vertical-align:middle;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp7 { vertical-align:middle;
padding:1px 8px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
p.hcp8 { margin-bottom:0; }
span.hcp9 { font-family:monospace; }
span.hcp10 { font-style:italic; }
td.hcp11 { vertical-align:TOP;
padding:1px 4px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp12 { vertical-align:middle;
padding:1px 15px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp13 { vertical-align:middle;
padding:0px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp14 { vertical-align:BOTTOM;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp15 { vertical-align:TOP;
padding:1px 8px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp16 { vertical-align:middle;
padding:1px 20px 1px 10px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp17 { vertical-align:middle;
padding:1px 4px;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px; }
td.hcp18 { vertical-align:middle;
text-align:center;
-moz-background-clip:-moz-initial;
-moz-background-origin:-moz-initial;
-moz-background-inline-policy:-moz-initial;
color:#000000;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px;
background-repeat:repeat;
background-position:0% 0%;
background-attachment:scroll; }
td.hcp19 { vertical-align:middle;
text-align:center;
-moz-background-clip:-moz-initial;
-moz-background-origin:-moz-initial;
-moz-background-inline-policy:-moz-initial;
color:#ffffff;
padding-left:1px;
padding-top:1px;
padding-right:1px;
padding-bottom:1px;
background-repeat:repeat;
background-position:0% 0%;
background-attachment:scroll; }
div.hcp20 { border:1px dashed rgb(47, 111, 171);
padding:1em;
color:#000000;
background-color:rgb(249, 249, 249);
line-height:1.1em;
font-family:"Lucida Console" , "Bitstream Vera Sans Mono" , Courier, monospace; }
span.hcp21 { color:seagreen; }
span.hcp22 { color:#E0302E; }
span.hcp23 { font-style:italic;
color:#6680CF; }
span.hcp24 { color:#804040; }
-->
</style>
</head>
<body class="ns-0 ltr">
<div id="globalWrapper">
<div id="column-content">
<div id="content">
<p><a name="top" id="top"></a></p>
<h1 class="firstHeading">Third-party Control Protocol</h1>
<div id="bodyContent">
<p id="siteSub">&#160;<script type="text/javascript" language="JavaScript1.2">//<![CDATA[
if (window.showTocToggle) { var tocShowText = "show"; var tocHideText = "hide"; showTocToggle(); }
//]]></script></p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Introduction" id="Introduction"></a></p>
<h1>Introduction</h1>
<p>This section is provided for Soundweb London users who
wish to provide their own user interface or control system
for a Soundweb London system. The user interface or control
system can be based on a PC running a custom application,
a dedicated show controller, a proprietary control system
such as Crestron or AMX, or even a custom piece of hardware.</p>
<p>The Soundweb London third-party control protocol builds
on the flexibility of the <span class="hcp1">RAW_MSG</span>
extension protocol introduced with Soundweb Original and
gives almost complete control of a Soundweb London network
via RS-232 or TCP/IP.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Interface_Options" id="Interface_Options"></a></p>
<h1>Interface Options</h1>
<p>Soundweb London devices accept third-party control commands
via RS-232 or TCP/IP. It is only necessary to connect
to a single device in a Soundweb London network. That
device will forward control messages to other devices
as necessary.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Serial.2FRS-232" id="Serial.2FRS-232"></a></p>
<h2>Serial/RS-232</h2>
<ul>
<li class="p"><p>The connection from the controller
to the Soundweb London device should be made using
a 3-wire null modem cable. In most cases it is fine
if the other pins are connected, but some controllers
will only work with 3-wire cables.<span style="display: none;">RS232</span></p></li>
</ul>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td rowspan="7" style="vertical-align: middle;
padding: 8px 60px 8px 20px; padding-left: 1px;
padding-top: 1px; padding-right: 1px; padding-bottom: 1px;"><p class="hcp4"><img src="Nullmodem.jpg" alt="Image:nullmodem.png" title="Image:nullmodem.png" border="2" class="hcp5"></p></td>
<td colspan="4" height="4" class="hcp6">&#160;</td>
</tr>
<tr>
<td colspan="2" width="15" bgcolor="#E0E0E0" class="hcp7"><p class="hcp4"><span class="hcp1">PC or Controller</span></p></td>
<td colspan="2" width="15" bgcolor="#E0E0E0" class="hcp7"><p class="hcp4"><span class="hcp1">Soundweb London</span></p></td>
</tr>
<tr>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">RX</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
2</p></td>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">TX</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
3</p></td>
</tr>
<tr>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">TX</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
3</p></td>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">RX</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
2</p></td>
</tr>
<tr>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">GND</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
5</p></td>
<td width="7" class="hcp6"><p class="hcp4"><span class="hcp1">GND</span></p></td>
<td width="7" class="hcp6"><p class="hcp4">Pin
5</p></td>
</tr>
<tr>
<td colspan="4" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
<tr>
<td colspan="4" height="4" class="hcp6">&#160;</td>
</tr>
</table>
<ul>
<li class="p"><p class="hcp8">Soundweb
London devices use 8-bit data bytes, no parity, and
one stop bit (i.e. '8N1').<br>
</p></li>
<li>The default bit rate is 115,200 bps. This can be
changed in <a href="MAINIntroduction.htm">HiQnet London
Architect</a> by clicking on the desired device in
the system layout, opening the Properties window,
and selecting the desired data rate. Other parameters,
such as whether the device will expect messages to
be acknowledged, can also be adjusted here.</li>
</ul>
<p><img src="Blu_serial_properties.jpg" alt="Image:blu_serial_properties.png" title="Image:blu_serial_properties.png" border="2" class="hcp5"></p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="TCP.2FIP" id="TCP.2FIP"></a></p>
<h2>TCP/IP</h2>
<ul>
<li class="p"><p>Soundweb London devices also accept
third-party control messages via TCP/IP connections
on port 1023. Refer to your controller's documentation
for more information on connecting to a device via
TCP/IP.</p></li>
</ul>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Protocol_Description" id="Protocol_Description"></a></p>
<h1>Protocol Description</h1>
<p>The Soundweb London third-party control protocol (also
called the 'Direct Inject' protocol) is a simple message-based
protocol. Each message consists of a start byte, a message
type ID byte, the message payload (which depends on the
message type), a checksum byte, and an end byte. On serial
connections, messages with a valid checksum are acknowledged
with an ACK byte, while messages with an invalid checksum
trigger a NAK response.</p>
<p>In a typical scenario, a controller might first send
a series of SUBSCRIBE messages to learn the current state
of the Soundweb London system. The Soundweb London device
would respond with a SET message corresponding to each
valid SUBSCRIBE message. The Soundweb London device will
also notify the controller with a SET message each time
a subscribed control parameter changes (unless the change
is made by the controller itself). The controller could
then send SET messages each time a control parameter should
be changed based on user interaction or controller automation.
When the controller is done controlling the Soundweb London
system, it sends UNSUBSCRIBE messages corresponding to
each SUBSCRIBE sent previously.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Message_Format" id="Message_Format"></a></p>
<h2>Message Format</h2>
<p>Soundweb London third-party control messages have the
following format:</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td width="8" bgcolor="#C0F0D8" class="hcp6"><p class="hcp4">STX</p></td>
<td width="8" bgcolor="#C0D8F0" class="hcp6"><p class="hcp4">ID</p></td>
<td width="21" bgcolor="#E0C0F8" class="hcp6"><p class="hcp4">Payload</p></td>
<td width="8" bgcolor="#F0EEC0" class="hcp6"><p class="hcp4">Checksum</p></td>
<td width="8" bgcolor="#F0C0C0" class="hcp6"><p class="hcp4">ETX</p></td>
</tr>
<tr>
<td bgcolor="#C0F0D8" class="hcp6"><p class="hcp4"><span class="hcp9">0x02</span></p></td>
<td colspan="3" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4"><span class="hcp10">Message body - see
below</span></p></td>
<td bgcolor="#F0C0C0" class="hcp6"><p class="hcp4"><span class="hcp9">0x03</span></p></td>
</tr>
</table>
<p>The message body is constructed in three steps:</p>
<ol>
<li class="p"><p class="hcp8">The ID and
Payload are assembled according to the appropriate
format for the given message type.<br>
</p></li>
<li><p class="hcp8">An XOR checksum of
the ID and Payload is appended.<br>
</p></li>
<li>Any control codes are escaped.</li>
</ol>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Message_ID" id="Message_ID"></a></p>
<h3>Message ID</h3>
<p>There are nine message types. The behavior of each is
described in the following table:</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td width="7" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">ID</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Message
Type</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Description</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x88</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_SETSV</span></p></td>
<td class="hcp3"><p class="hcp8">Set a control parameter.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x89</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESV</span></p></td>
<td class="hcp3"><p class="hcp8">Return the current
value of and subscribe to a control parameter.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8A</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESV*</span></p></td>
<td class="hcp3"><p class="hcp8">Unsubscribe from
a control parameter.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8B</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_VENUE_PRESET_RECALL</span></p></td>
<td class="hcp3"><p class="hcp8">Recall a Venue Preset.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8C</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_PARAM_PRESET_RECALL</span></p></td>
<td class="hcp3"><p class="hcp8">Recall a Parameter
Preset.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8D</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_SETSVPERCENT</span></p></td>
<td class="hcp3"><p class="hcp8">Set a control parameter
by percentage.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8E</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESVPERCENT</span></p></td>
<td class="hcp3"><p class="hcp8">Return the current
value of and subscribe to a control parameter
as a percentage of its total range.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x8F</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESVPERCENT*</span>
&#160;</p></td>
<td class="hcp3"><p class="hcp8">Unsubscribe from
a state variable previously subscribed as a percentage
of its total range.</p></td>
</tr>
<tr>
<td class="hcp3"><p class="hcp4"><span class="hcp9">0x90</span></p></td>
<td class="hcp3"><p class="hcp8"><span class="hcp1">DI_BUMPSVPERCENT</span>
&#160;</p></td>
<td class="hcp3"><p class="hcp8">Increment a control
parameter by the given signed percentage of its
total range.</p></td>
</tr>
<tr>
<td colspan="3" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
<tr>
<td colspan="3" class="hcp6"><p style="text-align: right;
margin-bottom: 0;"><span class="hcp10"><span class="hcp1">*DI_UNSUBSCRIBESV</span>
and <span class="hcp1">DI_UNSUBSCRIBESVPERCENT</span>
are not interchangeable.</span></p></td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Payload" id="Payload"></a></p>
<h3>Payload</h3>
<p>The payload varies slightly with each message type.
The message ID and payload together are 5 bytes for preset
messages, 13 bytes for all other messages (before any
control codes are escaped).</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td colspan="2" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Message
Type</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Payload
Format</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x88</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SETSV</span></p></td>
<td rowspan="7" class="hcp12"><p class="hcp8"><img src="Payload_format.jpg" alt="Image:payload_format.png" title="Image:payload_format.png" border="2" class="hcp5"></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x89</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESV</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8A</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESV</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8D</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SETSVPERCENT</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8E</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESVPERCENT</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8F</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESVPERCENT</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x90</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_BUMPSVPERCENT</span></p></td>
</tr>
<tr>
<td colspan="3" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td colspan="2" class="hcp6">&#160;</td>
<td rowspan="4" class="hcp12"><p class="hcp8"><img src="Payload_preset.jpg" alt="Image:payload_preset.png" title="Image:payload_preset.png" border="2" class="hcp5"></p></td>
</tr>
<tr>
<td width="7" class="hcp14"><p class="hcp4"><span class="hcp9">0x8B</span></p></td>
<td style="vertical-align: BOTTOM; padding: 1px 4px;
padding-left: 1px; padding-top: 1px; padding-right: 1px;
padding-bottom: 1px;" height="1"><p class="hcp8"><span class="hcp1">DI_VENUE_PRESET_RECALL</span></p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8C</span></p></td>
<td height="1" class="hcp11"><p class="hcp8"><span class="hcp1">DI_PARAM_PRESET_RECALL</span></p></td>
</tr>
<tr>
<td colspan="2" class="hcp6">&#160;</td>
</tr>
<tr>
<td colspan="3" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Address" id="Address"></a></p>
<h4>Address</h4>
<p>Control parameters (also called 'State Variables') on
a Soundweb London device are logically grouped into Virtual
Devices (corresponding to categories of objects, such
as Audio and Logic) and Objects (corresponding to individual
processing objects). Each Object is uniquely identified
on the Soundweb London network by its HiQnet address.
HiQnet addresses are typically represented in hexadecimal
and have the following format: <span class="hcp9">0x<span class="hcp10"><span style="color: #452BC5;">Node</span><span
style="color: #049A40;">VD</span><span style="color: #921880;">Object</span></span></span>.</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Field</p></td>
<td width="5" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Size</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Name</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Description</p></td>
</tr>
<tr>
<td nowrap="nowrap" class="hcp15"><p class="hcp8"><span class="hcp1">Node</span></p></td>
<td class="hcp3"><p class="hcp4">2</p></td>
<td nowrap="nowrap" class="hcp3"><p class="hcp8">HiQnet
Node Address</p></td>
<td class="hcp3"><p class="hcp8">The HiQnet node
address of the targeted Soundweb London device.
Each physical Soundweb London device has a unique
HiQnet node address assigned to it using the HiQnet
London Architect software. If the node field is
zero, the message will be sent to the device that
is directly connected to the controller via RS-232
or TCP/IP. Otherwise the message will be forwarded
to the corresponding device.</p></td>
</tr>
<tr>
<td colspan="4" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td nowrap="nowrap" class="hcp15"><p class="hcp8"><span class="hcp1">VD</span></p></td>
<td class="hcp3"><p class="hcp4">1</p></td>
<td nowrap="nowrap" class="hcp3"><p class="hcp8">Virtual
Device ID</p></td>
<td class="hcp3"><p class="hcp8">The ID of the targeted
virtual device. Objects (such as gains, mixer,
logic elements, etc.) within the Soundweb London
system are organized into Virtual Devices. A list
of the Virtual Devices in a Soundweb London DSP
device follows below.</p></td>
</tr>
<tr>
<td colspan="4" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td nowrap="nowrap" class="hcp15"><p class="hcp8"><span class="hcp1">Object</span></p></td>
<td class="hcp3"><p class="hcp4">3</p></td>
<td nowrap="nowrap" class="hcp3"><p class="hcp8">Object
ID</p></td>
<td class="hcp3"><p class="hcp8">The ID of the targeted
processing object. Each processing object, logic
object, etc. has a unique object ID.</p></td>
</tr>
<tr>
<td colspan="4" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Node" id="Node"></a></p>
<h5>Node</h5>
<p>The node address of a Soundweb London device is shown
in the Properties window when the device is selected in
the system layout. It is also shown in the Network window
when a device is selected in the network tree. See <a
href="Connecting&#32;to&#32;a&#32;Soundweb&#32;London&#32;network.html">Connecting
to a Soundweb London network</a> for more information
on changing a device's node address. The node address
is the first four hexadecimal digits of the HiQnet address.</p>
<p><img src="http://web.media.mit.edu/~benb/statics/bssmanual/MAIN/Network_view_node_address.jpg" alt="Image:Network_view_node_address.png" title="Image:Network_view_node_address.png" border="2" class="hcp5"></p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Virtual_Device" id="Virtual_Device"></a></p>
<h5>Virtual Device</h5>
<p>Each Soundweb London DSP device contains four virtual
devices. The Virtual Device ID is the third byte of the
HiQnet address, or the fifth and sixth hexadecimal digits.</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td width="7" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">VD</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Description</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x00</span></p></td>
<td class="hcp16"><p class="hcp8">Basic
settings</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x01</span></p></td>
<td class="hcp16"><p class="hcp8">Links</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x02</span></p></td>
<td class="hcp16"><p class="hcp8">Logic
objects</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x03</span></p></td>
<td class="hcp16"><p class="hcp8">Audio
processing objects</p></td>
</tr>
<tr>
<td colspan="2" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Object" id="Object"></a></p>
<h5>Object</h5>
<p>The Object ID is the last six hexadecimal digits of
the HiQnet address shown in the Properties window when
a processing object is selected in the device's audio
configuration.</p>
<p><img src="Object_id.jpg" alt="Image:Object_id.png" title="Image:Object_id.png" border="2" class="hcp5"></p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="State_Variable" id="State_Variable"></a></p>
<h4>State Variable</h4>
<p>Each control parameter of an Object is identified by
a State Variable ID. State Variable IDs are consistently
defined for each object type. For example, the mute control
of every Gain object always has State Variable ID <span class="hcp9">0x01</span>. If an object
has a large number of control parameters, it is possible
to use a formula to calculate the State Variable ID based
on input and/or output channels, rather than hard-coding
each control parameter ID. See <a href="Common&#32;Object&#32;and&#32;State&#32;Variable&#32;IDs.html">Common
Object and State Variable IDs</a> for a list of objects
and their corresponding State Variable IDs, including
formulas for calculating State Variable IDs for some objects.
The State Variable ID for a control parameter can be discovered
by selecting the desired object, opening the Properties
window, and clicking the desired control parameter in
the Parameters list of the Properties window:</p>
<table wrapperparagraphselector="P" cellspacing="0" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><img src="Gain_svid_from_properties.jpg" alt="Gain Object: Gain SV ID is 0x00" title="Gain Object: Gain SV ID is 0x00" border="2" class="hcp5"></p></td>
</tr>
<tr>
<td nowrap="nowrap" class="hcp3"><p class="hcp4"><span
style="font-size: smaller;">Gain Object: Gain
SV ID is 0x00</span></p></td>
</tr>
</table>
<p>The two-byte State Variable ID is always an unsigned
16-bit big-endian integer.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Data" id="Data"></a></p>
<h4>Data</h4>
<p>The four-byte data section is always a signed 32-bit
big-endian integer (i.e. the most significant byte is
transmitted first). The contents of the data section are
determined by the message type.</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td colspan="2" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Message
Type</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Data
Type</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x88</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SETSV</span></p></td>
<td class="hcp12"><p class="hcp8">Raw
control value</p></td>
</tr>
<tr>
<td colspan="3" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8D</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SETSVPERCENT</span></p></td>
<td rowspan="2" class="hcp12"><p class="hcp8">Percentage of control
range</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x90</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_BUMPSVPERCENT</span></p></td>
</tr>
<tr>
<td colspan="3" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x89</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESV</span></p></td>
<td rowspan="2" class="hcp12"><p class="hcp8">Zero for non-meter
SVs, subscription rate for meter SVs</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8E</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_SUBSCRIBESVPERCENT</span></p></td>
</tr>
<tr>
<td colspan="3" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8A</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESV</span></p></td>
<td rowspan="2" class="hcp12"><p class="hcp8">Zero</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8F</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_UNSUBSCRIBESVPERCENT</span></p></td>
</tr>
<tr>
<td colspan="3" height="1" bgcolor="#E0E0E0" class="hcp13">&#160;</td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8B</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_VENUE_PRESET_RECALL</span></p></td>
<td rowspan="2" class="hcp12"><p class="hcp8">Preset ID</p></td>
</tr>
<tr>
<td width="7" class="hcp3"><p class="hcp4"><span class="hcp9">0x8C</span></p></td>
<td class="hcp11"><p class="hcp8"><span class="hcp1">DI_PARAM_PRESET_RECALL</span></p></td>
</tr>
<tr>
<td colspan="3" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Raw_Value" id="Raw_Value"></a></p>
<h5>Raw Value</h5>
<p>Each type of control parameter (i.e. gain, mute, frequency,
time, etc.) has its own encoded format for raw values.
See Appendix A for information on calculating raw values.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Percentage" id="Percentage"></a></p>
<h5>Percentage</h5>
<p>The value of the control as a percentage of its total
range (i.e. 0 to 100) multiplied by 65536 to allow for
fractions of a percent. The accepted range of values is
0 to 6553600 for <span class="hcp1">DI_SETSVPERCENT</span>,
-6553600 to 6553600 for <span class="hcp1">DI_BUMPSVPERCENT</span>.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Subscription_Rate" id="Subscription_Rate"></a></p>
<h5>Subscription Rate</h5>
<p>The delay in milliseconds between updates sent by a
meter. The Soundweb London device will round this value
to 50ms increments. The rate must be zero when subscribing
to a non-meter control parameter. Control system and logic
performance may suffer if this value is too low.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Preset_ID" id="Preset_ID"></a></p>
<h5>Preset ID</h5>
<p>Each preset on a Soundweb London network is assigned
a unique ID when it is created. Once assigned, the Preset
ID will not change when other presets are added or deleted.
The message type corresponding to the preset's type (<span class="hcp1">DI_VENUE_PRESET_RECALL</span>
for venue presets, <span class="hcp1">DI_PARAM_PRESET_RECALL</span>
for parameter presets) must be used, as venue presets
and parameter presets may have the same ID.</p>
<p>Preset IDs are shown in square brackets next to each
preset in the design tree:</p>
<p><img src="Presets_in_design_tree.jpg" alt="Image:Presets_in_design_tree.png" title="Image:Presets_in_design_tree.png" border="2" class="hcp5"></p>
<p><span class="hcp10"><span class="hcp1">Note:</span>
Preset recall messages are broadcast across the network,
so unexpected results may occur if presets are recalled
with two separate HiQnet London Architect designs running
on the same physical network.</span></p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Checksum" id="Checksum"></a></p>
<h3>Checksum</h3>
<p>The checksum is a single-byte exclusive OR (XOR) of
all the bytes in the message body, computed <span class="hcp10">before</span>
control codes are escaped and <span class="hcp10">before</span>
<span class="hcp1">STX</span> and <span class="hcp1">ETX</span> are added.</p>
<p><span class="hcp10"><span class="hcp1">Note:</span>
If the checksum is a reserved control code it must be
escaped in the same way as bytes in the body of the message.
See Control Codes below.</span></p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Control_Codes" id="Control_Codes"></a></p>
<h3>Control Codes</h3>
<p>The following byte values have special meanings and
must be escaped if they occur within the message body.
If a byte in the message body is one of the control codes,
insert <span class="hcp1">ESC</span> (<span class="hcp9">0x1B</span>) before the
byte and add <span class="hcp9">0x80</span>
(decimal 128) to its value. Any other byte can be used
within the message body. Note that substitution must be
performed on the message body <span class="hcp10">after</span>
the checksum has been calculated and appended and <span class="hcp10">before</span> <span class="hcp1">STX</span>
and <span class="hcp1">ETX</span> are added
to the message, as the checksum itself may be a control
code in need of substitution.</p>
<table wrapperparagraphselector="P" cellspacing="2" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td width="7" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Code</p></td>
<td width="12" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Substitution</p></td>
<td width="7" bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Name</p></td>
<td bgcolor="#E0E0E0" class="hcp6"><p class="hcp4">Description</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x02</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B 0x82</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp1">STX</span></p></td>
<td class="hcp17"><p class="hcp8">ASCII
Start of Text</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x03</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B 0x83</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp1">ETX</span></p></td>
<td class="hcp17"><p class="hcp8">ASCII
End of Text</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x06</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B 0x86</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp1">ACK</span></p></td>
<td class="hcp17"><p class="hcp8">ASCII
Acknowledge</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x15</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B 0x95</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp1">NAK</span></p></td>
<td class="hcp17"><p class="hcp8">ASCII
No-acknowledge</p></td>
</tr>
<tr>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp9">0x1B 0x9B</span></p></td>
<td class="hcp6"><p class="hcp4"><span class="hcp1">ESC</span></p></td>
<td class="hcp17"><p class="hcp8">ASCII
Escape</p></td>
</tr>
<tr>
<td colspan="4" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Examples" id="Examples"></a></p>
<h1>Examples</h1>
<p>The following examples display the complete structure
of an actual control message and demonstrate a possible
approach to sending and receiving control messages.</p>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="A_Sample_Message" id="A_Sample_Message"></a></p>
<h2>A Sample Message</h2>
<p>This sample direct inject message will flash the locate
light on the device indicated by the address.</p>
<table wrapperparagraphselector="P" cellspacing="1" class="hcp2">
<tr>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
<td class="hcp3">&#160;</td>
</tr>
<tr>
<td rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Start</p></td>
<td rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Type</p></td>
<td colspan="6" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Address</p></td>
<td colspan="2" rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">State
Variable</p></td>
<td colspan="4" rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Data</p></td>
<td rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Check-<br>
sum</p></td>
<td rowspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">End</p></td>
</tr>
<tr>
<td colspan="2" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Node</p></td>
<td bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">VD</p></td>
<td colspan="3" bgcolor="#E0E0E0" class="hcp14"><p class="hcp4">Object</p></td>
</tr>
<tr>
<td width="5" bgcolor="#C0F0D8" class="hcp18"><p class="hcp8"><span class="hcp9">02</span></p></td>
<td width="5" bgcolor="#C0D8F0" class="hcp18"><p class="hcp8"><span class="hcp9">88</span></p></td>
<td width="5" bgcolor="#452BC5" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#452BC5" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#049A40" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#921880" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#921880" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#921880" class="hcp19"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#FCEECD" class="hcp18"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#FCEECD" class="hcp18"><p class="hcp8"><span class="hcp9">04</span></p></td>
<td width="5" bgcolor="#E8FBDD" class="hcp18"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#E8FBDD" class="hcp18"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#E8FBDD" class="hcp18"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#E8FBDD" class="hcp18"><p class="hcp8"><span class="hcp9">00</span></p></td>
<td width="5" bgcolor="#F0EEC0" class="hcp18"><p class="hcp8"><span class="hcp9">8C</span></p></td>
<td width="5" bgcolor="#F0C0C0" class="hcp18"><p class="hcp8"><span class="hcp9">03</span></p></td>
</tr>
<tr>
<td class="hcp6">&#160;</td>
<td colspan="13" bgcolor="#E0C0F8" class="hcp6"><p class="hcp4">The
bytes in the message body used to calculate the
checksum.</p></td>
<td colspan="2" class="hcp6">&#160;</td>
</tr>
<tr>
<td colspan="16" height="2" bgcolor="#E0E0E0" class="hcp6">&#160;</td>
</tr>
</table>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Sending_Messages" id="Sending_Messages"></a></p>
<h2>Sending Messages</h2>
<p>The following pseudocode procedure sends a correctly
formatted message by computing the checksum, escaping
control characters, and adding <span class="hcp1">STX</span>
and <span class="hcp1">ETX</span>.</p>
<div class="hcp20">
<p><span class="hcp21">char</span>&#160;checksum
= <span class="hcp22">0</span>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">&#160;/*&#160;Stores
the running checksum */</span><br>
<br>
send (<span class="hcp1">STX</span>)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Send
the start-of-text character */</span><br>
<br>
<span class="hcp24">for</span>&#160;each
character in message body&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Loop
through each character of the message */</span><br>
{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;checksum
= checksum XOR character&#160;&#160;&#160;<span class="hcp23">/*&#160;Add the current character
to the checksum */</span><br>
<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">if</span>&#160;(is_special
(character))<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(<span class="hcp1">ESC</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(character + <span class="hcp22">128</span>)&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Escape
special characters */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(character)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Send
non-special characters normally */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
}<br>
<br>
<span class="hcp24">if</span>&#160;(is_special
(checksum))&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Escape
the checksum if needed */</span><br>
{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(<span class="hcp1">ESC</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(checksum + <span class="hcp22">128</span>)<br>
}<br>
<span class="hcp24">else</span><br>
{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(checksum)<br>
}<br>
<br>
send (<span class="hcp1">ETX</span>)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Send
the end-of-text character */</span><br>
<br>
<span class="hcp24">if</span>&#160;(connected
via RS-232)&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">&#160;/*&#160;Wait
for the device to get the message */</span><br>
{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;waitfor
(<span class="hcp1">ACK</span> or <span class="hcp1">NAK</span>)<br>
}<br>
</p>
</div>
<p>&#160;</p>
<div class="editsection" style="float: right; margin-left: 5px;">
<p>&#160;</p>
</div>
<p><a name="Receiving_Messages" id="Receiving_Messages"></a></p>
<h2>Receiving Messages</h2>
<p>The following pseudocode procedure receives a message,
processes escaped control characters, and makes sure the
message is valid by verifying the checksum.</p>
<div class="hcp20">
<p><span class="hcp21">bool</span>&#160;got_escape&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">&#160;/*&#160;Indicates
whether the previous character was <span class="hcp1">ESC</span>
*/</span><br>
<span class="hcp21">char</span>&#160;checksum
= <span class="hcp22">0</span>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">&#160;/*&#160;Stores
the running checksum */</span><br>
<br>
on received character<br>
{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">if</span>&#160;(character
equals <span class="hcp1">STX</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;This
is the start of a new message */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;checksum
= <span class="hcp22">0</span>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Clear
the checksum */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;clear_message_buffer()&#160;&#160;<span class="hcp23">/*&#160;Clear
the message buffer */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;got_escape
= <span class="hcp22">false</span>&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Clear
the &quot;escape received&quot; status */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span>&#160;<span class="hcp24">if</span>&#160;(character
equals <span class="hcp1">ETX</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;This
is the end of a message, verify the checksum */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">if</span>&#160;(get_last_byte_in_message_buffer()
equals checksum)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(<span class="hcp1">ACK</span>)&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;The
received checksum matched the computed checksum */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;send
(<span class="hcp1">NAK</span>)&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;The
received checksum was invalid */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;got_escape
= <span class="hcp22">false</span>&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Clear
the &quot;escape received&quot; status */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span>&#160;<span class="hcp24">if</span>&#160;(character
= <span class="hcp1">ESC</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;got_escape
= <span class="hcp22">true</span>&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Set
the &quot;escape received&quot; status */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">if</span>&#160;(got_escape
= <span class="hcp22">true</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;The
last character was <span class="hcp1">ESC</span>
- this must be an escaped control code */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;add_byte_to_message_buffer
(character - <span class="hcp22">128</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;checksum
= checksum XOR (character - <span class="hcp22">128</span>)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp24">else</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;{<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;The
last character was not <span class="hcp1">ESC</span>
- this must be an ordinary byte */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;add_byte_to_message_buffer
(character)<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;checksum
= checksum XOR character<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;got_escape
= <span class="hcp22">false</span>&#160;&#160;&#160;&#160;&#160;&#160;<span class="hcp23">/*&#160;Clear
the &quot;escape received&quot; status */</span><br>
&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;}<br>
}<br>
</p>
</div>
<p><!-- Saved in parser cache with key bugs:pcache:idhash:2753-0!1!0!0!!en!2 and timestamp 20080206161223 --></p>
</div>
</div>
</div>
</div>
<p class="hcp8">&#160;</p>
</body>
</html>