[Aidan, Georgia, Jeff K]

Georgia and Jeff alerted me to some strange behaviour in the SR3 heater. The power monitor channel (PMON = product of IMON and VMON) is not reporting anything like the same power as the requested power (although it is correctly reporting the product of IMON and VMON).

The attached image shows that when PSET is changed from 5W to 4W, the voltage monitor channel changes from -12.2V to -14.4V. Even accounting for a possible error in the sign, the magnitude of this change makes no sense: a 20% reduction in power should correspond to a 10% reduction in voltage but we see an 18% increase in the magnitude of the voltage monitor. The VMON calibration shows that the OFFSET is set to zero.

I've asked TJ to look into the Beckhoff code that is calculating these monitor channels to try to determine if this is a software or hardware issue.