According to the USB control page the following commands need to have a VOLTAGE or CURRENT argument. Is that argument mV and mA or V and A?
"cal v VOLTAGE
Calibrates the ADC’s voltage gain. VOLTAGE should be the voltage across the Re:load Pro. Responds with ‘ok’.
cal i CURRENT
Calibrates the ADC’s current gain. CURRENT should be the current across the Re:load Pro. Responds with ‘ok’.
cal d CURRENT
Performs automatic DAC opamp offset trim, offset, and gain calibration based on the calibrated output of the ADC. Responds with ‘ok’. CURRENT is the maximum test current level to use in calibration.
From v1.6: No longer performs opamp offset trim calibration; this is now done with ‘cal t’ or manually with ‘cal O’
cal O [OFFSET]
Without an argument, returns the current opamp offset trim value, between 0 and 63 with a ‘cal O’ response. With an argument, sets the opamp offset trim.
cal t CURRENT
Performs automatic opamp offset trim calibration. Responds with ‘ok’. CURRENT is the maximum test current level to use in calibration."
After some fiddling it looks like I was doing some stuff wrong. The commands all appear to be in mV and mA.