The Pressure Control Module (PCM) will automatically self-adjust (tune) to the current conditions, or to compensate for changes in the control valves over time. Note that if there is a bad condition, the PCM will try to adjust for that.
View the control diagnostic screen at this menu path: Setup > Diagnostic > Control > Primary.
SUPPLY gas pressure, EXHAUST port pressure, PCM serial number, PCM firmware version and PCM coefficients can be viewed on the control diagnostic screen.
Bad conditions might be:
- Not having SUPPLY gas pressure ON when starting a test
- Low SUPPLY gas pressure
- SUPPLY gas pressure changing (dropping) during use
- Open TEST port (forgot to connect test devices or left a valve open)
- Very large volume on the TEST port
- Leak in test devices or open valve
- Leak in a connected Contamination Prevention System (CPS). If a CPS is connected, then ensure that it is enabled by this menu path: Setup --> Instrument Setup --> External Valves, ensure that CPS shows “Enabled”. If not, click “Not Enabled” to the right of the CPS label to change to “Enabled” to enable the CPS.
- Trying to control to a setpoint lower than 1 kPa (0.15 psi) in absolute mode with an 8270A modular pressure calibrator. The same limitation applies in gauge mode at the equivalent pressure (gauge = absolute - atm).
- Trying to control to a setpoint lower than 7 kPa (1 psi) in gauge mode with an 8370A modular pressure calibrator, or with an 8270A controller that does not have a vacuum pump on its EXHAUST port.
1. How to investigate if the control valves are leaking
- APPLY valve (increase pressure valve) leaking - Does the TEST pressure increase up to the SUPPLY pressure when in measure mode?
- RELEASE valve (decrease pressure valve) leaking - Does gas leak out the EXHAUST port when in measure mode (gas sound noticeable from EXHAUST port on rear manifold)?
2. What are expected ranges of voltage for Apply and Release Open Voltage?
"Apply Open Voltage" and "Release Open Voltage" typical values are 30 to 90 volts
3. When should "Tune Reset" be used?
Whenever control is not working well. Press [Tune Reset] on the control diagnostic screen to reset the control coefficients to factory values. Then control to the following setpoints to tune the control to the present conditions (all values in MPa): 10, 20, 30, 40, 30, 20, 10. Values in psi are 1500, 3000, 4500, 6000, 4500, 3000, 1500. With an 8370A controller you can do higher setpoints in 2000 psi increments. Then retry setpoints that were previously failing.
Deviation values of -999 are normal after a "Tune Reset" is performed.
If voltages are still outside of the expected range after some operation, and control is poor, then there may be an issue with the PCM.
4. When should "Tune Reset" not be used?
Tune Reset will likely not fix an "Error 547 Valve Error". This error is likely caused by a module's slot isolation valve not closing fast enough to prevent the module from exceeding its pressure limit value. This is a software/firmware issue that will be improved in a future firmware release. Here are some steps to prevent this:
- Reduce the control slew rate to <50% of maximum value (<516 MPA/Min). This limits the occurrence but does not eliminate it.
- Change controller to “fixed” mode if the test uncertainties can support it.
Other than external o-rings, there are no user serviceable parts inside the PCM-STD-40M or PCM-STD-100M. Return of the PCM to the Everett, Washington, USA service center for evaluation is required. See service information at this link, Fluke Calibration Service and Support