Basic Message Structure - Christie D4K40-RGB Technical Reference

Basic message structure

Understand the component fields that comprise a standard ASCII message.
Components
Start and end of message
Prefix characters (optional) To acknowledge that D4K40-RGB has responded, and/or maximize message
Function code
+Subcode
Request/reply symbols
Data
D4K40-RGB Technical Reference–Serial Commands
020-102972-02 Rev. 1 (01-2019)
Copyright 2019 Christie Digital Systems USA, Inc. All rights reserved.
©
Description
Every message begins with the left bracket character and ends with the right bracket
character.
If the start character is received before an end character of the previous message,
the partial (previous) message is discarded.
integrity, insert one or two special characters before the three-character function
code:
• $ (Simple Acknowledgment)—Causes a dollar sign ($) character to be sent from
D4K40-RGB when it has finished processing the message.
• # (Full Acknowledgment)—Causes an echo of the message as a reply to be sent
from D4K40-RGB when it has finished processing the message.
• & (Checksum)—Allows a checksum to be put as the last parameter in the
message for verification at D4K40-RGB.
The D4K40-RGB function you want to work with, such as channel selection or
gamma, is represented by a three-character ASCII code (A-Z, upper or lower case).
This function code appears immediately after the leading bracket that starts the
message. In messages sent to D4K40-RGB that do not have a subcode, a space
between the function code and the first parameter (or special character) is optional.
The D4K40-RGB function you want to work with may have one or more subcodes
that allow you to select a specific source, image, channel or subfunction.
The subcode is represented by a four-character ASCII code (A-Z, upper or lower
case, and 0-9). This subcode appears immediately after the function code, with a
plus sign (+) character to separate the code and subcode. If there is no subcode, the
plus sign (+) is also omitted. In messages sent to D4K40-RGB that have a subcode,
a space between the subcode and the first parameter (or special character) is
optional.
If the controller is requesting information from D4K40-RGB, a question mark (?)
appears directly after the function code. If D4K40-RGB is replying, an exclamation
mark (!) appears directly after the function code. For set messages to D4K40-RGB,
neither of these characters appear—data directly follows the code and subcode.
A request for information is represented by a question mark (?) that appears directly
after the function code. A reply is represented by an exclamation mark (!) that
appears directly after the function code or subcode, if one is provided. The first
parameter located after the exclamation mark (!) reply character cannot have a
space, for example (PWR!000).
The value for a given D4K40-RGB state, such as on or off, appears in ASCII-decimal
format directly after the request/reply symbol. You can add an optional space after
the symbol—such as before the data—in a set message, but data in replies follow the
exclamation mark (!) symbol without a space. Other details to remember about
data:
• All values returned by D4K40-RGB (reply messages) have a fixed length,
regardless of the actual value. For a specific parameter, the length is always the
Communicating with D4K40-RGB
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