Inficon VGC501 - Communication Protocol

tina96e1-b (2016-12) VGC501_VGC502_VGC503.om 67
Messages are transmitted to the VGC50x as ASCII strings in the form of mnemonic
operating codes and parameters. All mnemonics comprise three ASCII characters.
Spaces are ignored. <ETX> (CTRL C) clears the input buffer in the VGC50x.
HOST VGC50x Explanation
Mnemonics [and parameters] –––––––––>
<CR>[<LF>] ––––––––––––––––––––––>
Receives message with "end of
message"
<––––––––––––––––– <ACK><CR><LF> Positive acknowledgment of a re-
ceived message
When requested with a mnemonic instruction, the VGC50x transmits the measure-
ment data or parameters as ASCII strings to the HOST.
<ENQ> (CTRL E) must be transmitted to request the transmission of an ASCII
string. Additional strings, according to the last selected mnemonic, are read out by
repetitive transmission of <ENQ>.
If <ENQ> is received without a valid request, the ERROR word is transmitted.
HOST VGC50x Explanation
Mnemonics [and parameters] –––––––––>
<CR>[<LF>] ––––––––––––––––––––––>
Receives message with "end of
message"
<–––––––––––––––––- <ACK><CR><LF> Positive acknowledgment of a re-
ceived message
<ENQ> -––––––––––––––––––––––––> Requests to transmit data
<––––––––––––––– Measurement values
or parameters
<––––––––––––––––––––––– <CR><LF>
Transmits data with "end of mes-
sage"
: :
<ENQ> –––––––––––––––––––––––––> Requests to transmit data
<––––––––––––––– Measurement values
or parameters
<––––––––––––––––––––––– <CR><LF>
Transmits data with "end of mes-
sage"
The strings received are verified in the VGC50x. If an error is detected, a negative
acknowledgment <NAK> is output.
HOST VGC50x Explanation
Mnemonics [and parameters] –––––––––>
<CR>[<LF>] -–––––––––––––––––––––>
Receives message with "end of
message"
***** Transmission or programming error *****
<–––– <NAK><CR><LF> Negative acknowledgment of a re-
ceived message
Mnemonics [and parameters] ––––––––->
<CR>[<LF>] –––––––––––––––––––––>
Receives message with "end of
message"
<–––––––––––––––– <ACK><CR><LF> Positive acknowledgment of a re-
ceived message
5.2 Communication
Protocol
Transmission format
Transmission protocol
Reception format
Reception protocol
Error processing
Error recognition protocol