Varian 990 dCLD II, Operation Manual

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A-1
Model 990 dCLD II Component Leak Detector
Appendix A. Communications Protocol
This appendix defines the technical specifications for the RS-232 protocol to be used with
the 990 dCLD II Component Leak Detection System.
A.1 Protocol (RS-232)
The 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 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. Do not explore
this feature.
Words that begin with the ? character are inquiries for the controlling device to determine
the current state or value of a leak detector parameter. Words that begin with PUT are com-
mands for the controlling device to set the current state or value of a volatile leak detector
parameter. Words that begin with
INIT- are commands for the controlling device to set
non-volatile leak detector parameters. Other commands do not require a parameter, do not
begin with any special character(s), and simply do what they say they do.
Successful inquiries respond with data as specified in the following tables followed by a
space, then:
ok <CR><LF>. Unsuccessful inquiries respond with the offending inquiry fol-
lowed by a space, then: #? <CR><LF> (line feed, <LF>). Certain commands are restricted
from use while PARALLEL ENABLE is active; these commands respond
cant <CR><LF>.
Inquiries, parameters, and commands can be concatenated. Each word or numeric parame-
ter 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 com-
mands and inquiries following the failed word are ignored; all parameters are discarded.