See the below Excel file that shows the 6270A/8270A/8370A outputs that can be recorded during a COMPASS test. Select outputs (quartz sensor, fast sensor, barometer(s), etc.) from the PCM and selected PMMs can be logged during a COMPASS test. It should be useful for troubleshooting control/measure problems to a particular sensor in a PMM or PCM.
The database only shows 6270A but the commands are the same for 8270A and 8370A controllers.
See this article for a remote command to send to a PM600 module in the 6270A chassis to query its frequency counts.
PM600 module frequency counts - Check them in 6270A/8270A/8370A chassis