1 command, 1 command packet (host to composer elite message), 2 response – INFICON Composer Elite Gas Concentration Monitor User Manual
Page 88: Section 5.5.1
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Composer Elite Operating Manual
5.5.1 Command
This section describes the command format.
See
section 5.6, Communication Commands, on page 5-27
for details on specific
command IDs.
The message received by Composer Elite contains a data packet preceded by a
length and terminated by a checksum.
Composer Elite will always send a response to any command it receives.
5.5.1.1 Command Packet (Host to Composer Elite Message)
Length . . . . . . . . . . . . . . . . . . . . . . . 2 bytes Low / High (not including checksum
or length bytes). Numeric value representing
the number of characters in the command. In
order of transmission, the low byte will
precede the high byte. Normally, the number
for characters will be less than 9. In this case,
the low byte will contain the character count
while the high byte will have zero value.
Message . . . . . . . . . . . . . . . . . . . . .
Checksum . . . . . . . . . . . . . . . . . . . . 1 byte, sum, modulo 256, of all bytes, not
including length. Modulo 256 is the numeric
value from 0 to 255 representing the modulo
256 remainder of the sum of the values of the
ASCII codes that comprise the command.
5.5.2 Response
This section describes the response format that is returned in the data field of the
response message. See
section 5.6, Communication Commands, on page 5-27
for
more details on responses. The message sent by Composer Elite contains a data
packet preceded by a length and terminated by a checksum. See
for a detailed description of the received message structure.
If a command generates an error in response, an error code is returned (see
) in the Response Message and the SS bit in the status byte (see
) is set to 0. The SS bit is set to 1 indicating successful
completion of the received command.