Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
3-20
3.6 Operation via Rear Panel
Once setup is complete and the 990 dCLD II is warmed up, operation can be turned over
to the PLC by asserting PARALLEL ENABLE. Monitoring operations can take place using the
optional front control panel or PLC, or by issuing commands using a host computer
connected to the host serial port.
3.6.1 PARALLEL ENABLE
PARALLEL ENABLE turns control of the 990 dCLD II over to the PLC. Operations can be
monitored by issuing commands using a host computer connected to the host serial
port but most parameter values cannot be changed. If a command is issued that is not
allowed once PARALLEL ENABLE is asserted, the system responds
cant . See Appendix A
“Communications Protocol”.
If the optional front control panel is installed, you can monitor operations via the bar
graph display, the SPEC-TUBE PRESSURE display, and view the HOME and SYSTEM
INFORMATION screens on the touch panel, but, again, you cannot change parameter
values. The CALIBRATE, READ STANDARD LEAK, and ZERO buttons are not functional.
If you have set AUDIO to ON during setup, it remains operational, however you cannot
change its set point value. If you attempt to initiate an action from the optional front control
panel that is not allowed once PARALLEL ENABLE is asserted, you hear a double beep. See
Appendix B “Customer Accessible Inputs and Outputs”.
To remove control from the PLC, you must de-assert PARALLEL ENABLE. Even if the system
is shut down with PARALLEL ENABLE asserted, control remains with the PLC.
NOTE
If PARALLEL ENABLE is asserted, but the ?STATUS<CR>
response contains RDY/, indicating that the 990 dCLD II is not
able to measure a leak rate, check to see if IDLE is enabled. If
IDLE is enabled (see Table 2-11 on page 2-15 or Appendix A
“Communications Protocol”), the control unit is waiting for the
RUN command.