Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Communication Errors 6-9
SRS Residual Gas Analyzer
Communication Errors
Communication errors are signaled to the user flashing the Error LED a few times, setting
Bit 0 of the STATUS error byte and setting the error-specific bits of the RS232_ERR
error byte .
Many different circumstances can result in a communication error being reported after a
command string is received by the RGA. Some problems are detected early by the
command handler and result in the command never being executed. Other errors are
found later, during the actual command execution, and they result in the execution being
immediately halted.
The following is a list of the communication errors that might be encountered during the
analysis and execution of a command, including the specific ways in which they are
reported:
Command errors
Bad Command Name : The first two characters in a command string must be letters
(case insensitive) and must be part of the Command Set, otherwise the Error LED is
flashed, Bit 0 of RS232_ERR and Bit 0 of STATUS are set, and no command is
executed.
Command-too-long error : 14 characters are received over RS232 without a <CR> ever
being detected. The Receive buffer is flushed, Bit 2 of RS232_ERR and Bit 0 of
STATUS are set, and no command is executed.
Note that the LED is not flashed for this
error (only exception to the rule!) .
Parameter errors
Bad-Parameter error : Many different possibilities lead to a bad-parameter error.
x
The number parameter is out of the command's acceptable range.
x
A ““?”” is not strictly followed by <CR> in a Query command.
x
A ““*”” is not strictly followed by <CR> in a Default command.
x
A non-zero fractional part is found in a parameter that can only be an integer.
x
No parameter is found in a command that strictly requires one.
x
A parameter other than a ““?”” is found in a Query-only command.
x
A default parameter value is used with a command that does not have one
defined.
All Bad-Parameter errors are reported flashing the Error LED, and setting Bit 1 of
RS232_ERR and Bit 0 of STATUS. No command is executed.
Parameter-conflict error : When the parameter is in conflict with some other related
parameter value which pre-existed in the RGA head, the Error LED is flashed, Bit 6 of
RS232_ERR and Bit 0 of STATUS are set and the command is not executed.
Jumper Protection violation
Some calibration related commands are subject to jumper protection. Jumper JP100 on
the digital (i.e. top) board of the RGA electronics box can be used to enable/disable some
of the tuning features of the instrument. The jumper setting is checked before the
command is executed and if calibration is disabled, the Error LED is flashed, Bit 5 of
RS232_ERR and Bit 0 of STATUS are set, and the command is not executed. The