Andrea C

So, you will generate V and I data as function of some changing amount of mechanical stress?

For voltage, how high is high?  I suspect the sample also has high source impedance.  Therefore your volt meter needs input R spec larger than the source R to avoid loading errors.  Suggest the electrometer 6514 or 6517B.
Alternatively, a SourceMeter with low current ranges can be put into force 0 amps and limit voltage to some value higher than what you expect to measure.  Something like 2636B or 2635B has 1nA source range and offers quite good input R when behaving like volt meter good up to 200V.  Use 2657A if you need higher voltages.

By definition, a good v-meter has zero current flowing into or out of the meter.  So makes it not feasible to also measure the current on those same connection points with same instrument.  Unless the instrument is a SourceMeter, then it can change its configuration and force 0 V with current limit higher than you need to measure.
But understand I am describing two sequential measurements:  measuring V when force 0 Amps, then measuring I when forcing 0 V.  Can this work for you?

If envisioning two meters, how will you connect them?  Seems the amp meter will compete with the V meter for what the charge stored on your sample should do.

 

Not sure about pyMeasure and what actual SCPI commands it is sending to the 2400.
Looks like a loss of synchronization between the code and the instrument state since the error handler is itself throwing an error!

But since it is working mostly, I am wondering if baud rate of the RS-232 is playing a role.
On our old forum, there are some posts about dodgy RS-232 behavior at the fastest baud rate.  
Try slowing down to 19K baud rate.

If trouble persists, can you reduce the code into smaller bit that shows the issue?
Alternately, try using pySerial or pyVISA and directly send the SCPI commands understood by the 2400.

There is a Verification procedure and a separate Adjustment procedure.
When I used "tweak" I was thinking to carry out the Adjustment procedure.

For just the DC Amps, you've indicated the zero is out of tolerance.
Is it only 10uA range, or is the 100uA range also affected?
What about the full scale 10uA level?  Is that in spec?  Have you adjusted it whether it seems to need it or not?

And I was just guessing that perhaps the adjusted DCV zero might have some impact on the DC Amps A/D converter readings too.

If it continues to be out of tolerance, it seems an RMA for service to understand root cause is needed.

 

Hi Sergey,

The tspnet.write is not limited to just a few characters.  Not sure what the upper limit is, but is not 5.
Here is some sample code where the feature is used to interact with a Watlow temperature controller and many of the commands used there with tspnet.write are longer than 5 characters.

https://github.com/tektronix/keithley/tree/main/Instrument_Examples/DAQ6510/Use_the_DAQ6510_to_Control_a_Temperature_Chamber

Sometimes we have to deal with string is really a null terminated array of characters.
Google up ASCII (decimal) code for certain character.  the Zero is 48.  Null is 0.
Line feed is 10;  Carriage Return is 13.


 

Double checking:  when you access the zero, are you open circuit/not connected to your current source standard?

Prior to the DC Amps adjustment, did you first do the DC Volts?
The DC volts procedure has both a zero and full scale procedure step, whereas DC Amps has only full scale.
Perhaps tweaking up the DCVolts offset will impact the DC Amps offset.

Internally, the amps function is measuring the volts across a resistive shunt, so DC Volts could be related.

If you have done both DCV and the Amps is still out of tolerance, I suggest you contact your local sales office/service center.

As for the manual section I referenced, I see it is gone from what is presently posted on tek.com for the 6485.
I have some older revisions on my computer.

I'll upload the relevant pages for the topic of how the source R and C of the DUT interacts with the picoamp meter (or electrometer) current measure functionality.

Is likely to be due to the different capacitance of your photodiode if at 0V vs some reverse bias.
The DUT C will be larger at 0V.

In 6485 Instruction Manual, look at section noise and source impedance in Appendix I.
It gives a nice treatment of the topic in how the R and C of the DUT interacts with picoammeter gain.
If it is too much C, adding some additional series R can mitigate in some cases.  Just need to account for the I*R drop on the added R.

What sort of cable do you use?  How long?  It too is contributing some C.

Hi Jan,
I wanted to let you know I did duplicate the stalled scan once.  But is very intermittent.
I have opened a bug report for it in our quality system.

For the csv files it does generate, if you compute the delta on the reported time of each scan, does it increase from the expected 2 seconds as the file accumulates rows?

Andrea

Is it just the touch aspect, or no display activity at all?
If Windows is corrupted and cannot run, you could try a system restore.
During boot, press F11 when you see the message about Acronis True Image.
The as-shipped factory image is there.
NOTE:  this will wipe away your existing content in projects or custom user libraries.

You may need to contact your closest office/service center.

We will need to dig into this one a bit.

Question:  if not logging to USB, would the long duration scan operate without any issue?  Do you have opinion about that?