Christie TruLife+ Griffyn 4K32-RGB Technical Reference page 13

Message Description
requirement
There are two types of acknowledgments:
This is a quick way to confirm success with set messages and is useful with long distance
communication links or where the projectors and/or images are not visible from the
controller. Acknowledgments can also be a type of flow control.
Checksums For maximum message integrity, add a checksum character ampersand (&) just after the
start code bracket. You must also include the correct checksum total (0-255) just before
the end code bracket. Make sure to add a space before the calculated checksum to
separate it from the last data parameter:
The checksum is the low byte of the sum of the ASCII values of all characters between the
start bracket and the beginning of the checksum, but not including either. It does include
the space in front of the checksum.
Calculate the checksum for the above set contrast to 64 command as follows:
CHECKSUM EXAMPLE = & + c + o + n + 6 + 4 + 'space'
Christie TruLife+ collects all of the message bytes as defined in the first byte of the
message, then creates its own checksum value for comparison with the checksum included
in the controller's message. If the values match, the message is considered to have been
correctly received; otherwise, the message is discarded.
Note the following:
Error messages
If a command cannot be performed, a descriptive error identifying the problem appears.
For example, the following message indicates a syntax error:
(ITP) - (65535 00000 ERR00005 "ITP: Too Few Parameters")
Christie TruLife+ Technical Reference–Serial Commands
020-103316-01 Rev. 1 (09-2020)
Copyright © 2020 Christie Digital Systems USA, Inc. All rights reserved.
• Simple Acknowledgments—Insert a dollar sign ($) character just after the start code
bracket. This only returns a $. This only returns a dollar sign ($) on success, or a
caret (^) on failure (NAK).
• Full Acknowledgments—Insert a hash (#) character just after the start code bracket.
This returns the message sent, as a reply.
= 26h+63h +6Fh +6E h +36h +$34h +$20h
= 01F0h
= F0h when only the low byte is used
= 240
• h indicates a hex number.
• If a request message has a checksum, so does the reply.
• If using both acknowledge and checksum, either character can occur first.
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