MKS 651C, Instruction Manual, Page: 77 / 172

Chapter Six: Remote Operation RS-232 Commands and Requests
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Responses Sent from the 651 Controller to the Computer
Responses sent from the 651 controller to your computer are shown in the last column of
Table 27, page 134. The format of responses sent by the 651 controller to the computer will
appears in the table as:
response value
where
response
is a label that allows you to identify the response and value is the
information requested.
Note
Controller responses do not contain spaces. Any spaces shown in the
response syntax are simply used to improve readability.
The 651 controller appends a carriage return-line feed to the end of every
response.
For example, the controller’s response to the R1 request for the value of set point A is shown in
the table as:
S1 value
where value is a % of F.S.
To report a set point of 3 Torr on a 10 Torr sensor, the controller sends:
S130
Priority of Command Execution
Each RS-232 command is executed in the order that it is received. There is no prioritization of
RS-232 commands as is the case with digital logic commands. In fact, the appropriate RS-232
command will override a high priority digital logic command. For example, a valve being held
closed with a digital logic command can be commanded to control to the level of set point A
with the appropriate RS-232 command.
The RS-232 commands generally execute within 25 milliseconds or less with the exception of
the following:
•
T (set point type) and F (pressure unit) commands can take up to 100 milliseconds to
execute
•
J (valve calibration) and L (learn function) commands can take several seconds to
execute