I cannot get the Meter window to correctly apply the null offset to the displayed value in the latest version.
I am using PicoScope 5.13.1 (downloaded 2 days ago) with an ADC216. When I display a meter in 10 mV, 20mV, 50 mV, or 100 mV ranges, the meter window reads -0.546mV on channel A and +0.196 mV DC on channel B AFTER a null offset is performed - while the inputs are still shorted.
The equivilent DC measure functions on the Scope window go to zero (well, actually 0.0002 mV which is close enough!) after a null offset. So, I know the hardware is actually able to see and measure zero. The measure functions on the scope screen are always within 0.05% F.S. of my calibrator after a null offset, but the meter will always be off by about -0.546mV on channel A and +0.196mV on channel B. So, the offset is staying in the displayed meter measurements.
I have tried selecting Null Offset with meter window active and with scope window active. No difference. I tried both auto-scale and manually selecting scales for the meter and for the scope. No difference. I tried each channel. No difference. I also tried using 2 different shorts constructed of different materials, and the null volts function on a calibrator in case the issue was thermal EMF. No difference. I also tried rebooting the computer (a Compaq laptop running Windows ME). No difference.
I am connected to the ADC216 through the parallel port with no other devices attached. The only software loaded after boot-up is PicoScope.
BTW, I think your marketing group should consider revising the accuracy specifications of the ADC 216. It consistently measures much better than the advertised 1%; actually it is better .25% F.S. except in the 10 and 20mV scales where it is about 0.25% F.S +/- 0.5 mV.
If your specs were in line with the unit's actual performance and there were a published verification protocol (and/or calibration procedure!), it could be sold as a standard for field calibration of sensors. We've been using it for that purpose and it is way better than toting around a "portable oscilloscope." However, we had to verify performance on a precision calibrator before and after every use for months before the quality auditor would accept that it actually is much better than specified.