INFICON Guardian EIES Controller - Manual (Page 147)

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Guardian Co-Deposition Controller Operating Manual
7.3.3.1 V3.XX Controller Command/Response Format
The V3.XX controller command format is: (Command) (Data) (LF)
Where:
(Command) = ASCII command letter
(Data) = command parameters
(LF) = Hex 0A (end of message)
The V3.XX controller response format is: (Command) (Data) (LF)
Where:
(Command) = the command the message is responding to
(LF) = Hex 0A (end of message)
7.3.3.2 V4.XX Controller Command/Response Format
Version 4.XX and higher differs from V3.XX by adding error checking characters
before and after the message.
NOTE: V4.XX and higher also adds an additional communication timeout
requirement. If the controller does not receive any communications for
3 seconds, it goes into a safe mode where all PMT, Sensor and Control
Output voltages are set to zero. This prevents potentially dangerous
operation during power outages or computer failures.
The V4.XX and higher controller command format is:
The command protocol sent to the instrument is:
<sync character> <length character> <1 to n data characters> <space>
<CRC1><CRC2><LF>
The sync character is always an exclamation point '!'. Following the sync character
is the length character. This is the number of characters in the packet (not counting
the sync and CRC characters). The length character has a decimal 34 added to it
so there cannot accidentally be a sync character (!) embedded in the packet.
NOTE: Packet length can not exceed 220 characters ( 255-35).
Following the length character are the command and data characters as detailed
later in this section. After the data come two CRC characters.
The Guardian will return a CRC in its response computed with the same algorithm.