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VS Series Helium Mass Spectrometer Leak Detectors

DRAFT 4/23/15

A-1

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.

Agilent Technologies VS Series User Manual

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