Calibration of the PMMs can be accomplished using either of these recommended methods:
Method 1 - Using the Cal Sled accessory for a partial or fully automated process with COMPASS for Pressure calibration software. The Cal Sled is also known as the PMM-CAL-KIT-20M, or -40M for the higher pressure modules. The benefit of using the Cal Sled is that it allows the 6270A (or 8270A, 8370A) to remain in operation with the other PMMs while a module is calibrated. Calibration operations can be manually performed using discrete remote commands or they can be fully automated using COMPASS for Pressure software.
For a fully automated calibration using the Cal Sled, see this article:
PMM Automated Calibration: Cal Sled Method
Method 2 - Calibrating a PMM while it is installed in the chassis. This approach allows for a traditional manual approach where the measurement output of the PMM can be viewed on the front panel screen. It also allows for an operator to use discrete remote commands to query the pressure measurement. If automation is desired then there is an option to fully automate the calibration and adjustment process while the PMM remains in the chassis using COMPASS for Pressure software. The benefit of performing a calibration with the PMM in the chassis is simplification of hardware - a reference calibrator is installed where a DUT is traditionally plumbed to the 6270A. A downside to the in-chassis method is it takes the entire chassis out of operation while a PMM is being calibrated.
See this article for instructions on using the fully automated, in-chassis process with COMPASS for Pressure calibration software:
PMM Automated Calibration: In-Chassis Method
The 6270A service manuals describe a two point onboard calibration process using the front panel menus. As of the date of this publication this method has known short comings and is not a recommended method for calibrating the PMMs. Please reach out to Fluke Calibration's pressure technical support team for more information.