Appendix A. Communications Protocol - Agilent Technologies VS Series Operation Manual

VS Series Helium Mass Spectrometer Leak Detectors

Appendix A. Communications Protocol

This appendix defines the technical specifications for the RS-232 protocol used with the
leak detector and describes the customer-configured inputs/outputs.
A.1 Protocol (RS-232)
RS-232 ports operate at 9600 baud, 8 bits, no parity, and one stop bit.
All characters transmitted to the leak detector are echoed by the leak detector. Commands,
inquiries, and strings of both commands and inquiries must be terminated by a carriage
return <CR>; the carriage return is echoed as a space character.
The maximum length of the input is 80 characters; if no carriage return has been received
before the 80th character, execution of the command string begins anyway.
Words that begin with:
? are inquiries for the controlling device to determine the current state or value of a
❑
leak detector parameter.
PUT- are commands for the controlling device to set the current state or value of a
❑
volatile leak detector parameter.
INIT- are commands for the controlling device to set non-volatile leak detector
❑
parameters.
Other commands do not require a parameter and do not begin with any special characters.
Successful inquiries respond with data, followed by a space, then: ok<CR><LF>, as
specified in the tables of this appendix. Unsuccessful inquiries respond with the offending
inquiry followed by a space, then: #?<CR><LF> (line feed, <LF>).
Inquiries, parameters, and commands can be concatenated. Each word or numeric
parameter is followed by one or more spaces. The string is terminated by a <CR>, which
causes execution to begin.
Successful strings respond with the specified data for the input inquiries in the order the
inquiries were issued, followed by: ok<CR><LF>.
Unsuccessful strings respond with the first offending command followed by a space,
then: #?<CR><LF>. All commands and inquiries following the failed word are ignored;
all parameters are discarded.
Table A-1 on page A-5, Table A-2 on page A-8, Table A-3 on page A-11, and Table A-4 on
page A-11 outline the available control and query commands.
A-1