INFICON IC/5 Thin Film Deposition Controller - Manual (Page 151)

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IC/5 Operating Manual
7.6.1 INFICON Message Formats
There are two message formats for the serial ports and one for the IEEE488 port.
All messages are comprised of byte serial information. The byte values represent
command or response characters, control characters or numeric values.
Mnemonics will be used to describe the portions of each message format.
NOTE: These mnemonics are not part of the message stream; they are used to
represent specific ASCII codes, characters or numeric values that
comprise the message stream.
Serial With No Checksum Format
Host to Instrument Message
(command)
Instrument to Host Message
(response) or
(nrc)
Table 7-4 Mnemonics
Mnemonic Meaning
ASCII code 2 for Start of Transmission
ASCII code 6 for Positive Acknowledgment
ASCII code 21 for Negative Acknowledgment
ASCII code 10 for Line Feed (EOT byte for IEEE488)
(command) ASCII character codes representing the host’s command as
described in Section 7.7
(response) ASCII character codes representing the instrument’s response as
described in Section 7.7
(nrc) A negative response code; used for error responses to a host
command. Section 7.7.7 lists the error codes and their meaning.
(checksum) Numeric value from 0 to 255 (one byte) representing the modulo 256
remainder of the sum of the values of the ASCII codes that comprise
the message or response including the ACK or NAK code.
(count) Numeric value from 0 to 16,383 (two bytes) representing the number
of characters in the command or response. Two byte values, high
and low order, are required to represent this number. In order of
transmission, the high byte will precede the low byte. For most
commands, the number of characters will be less than 256. In this
situation the low byte will contain the character count while the high
byte will have zero value.