Unfortunately, we are having difficulties with the Keithley SMU 2450 and its operation with SweepMe! for some time now. In our setup we move a robot head to the individual samples in a matrix arrangement and then measure current-voltage curves for each sample. This can result in many measurements and long runtimes (up to 24 h). We changed the SMU 6 months ago and have had the below-mentioned problems ever since.
Two errors occur during our measurement, namely a timeout (VI_ERROR_TMO (-1073807339)) and a critical error (VI_ERROR_IO (-1073807298)). We suspect that both errors have a similar cause but cannot confirm this. Also, not all measurements
are affected, which makes it difficult to reproduce the error.
basically it is an error from the VISA runtime that is forward by the pyvisa library.
The first error is the VI_ERROR_IO (-1073807298) which probably is the main error. The timeout error, I guess, is just a follow up error.
I think there is not much that you can change in the SweepMe! driver, because it looks like deeper lying cause for the problem than just sending the wrong command, especially because the driver works for other users as is.
What you could try as well:
Install the latest visa runtime version that might include some bug fixes that are related to your problem.
Do you use USBTMC or TCPIP communication? Try another one to see whether the problems persists.
You can always google for the VI_ERROR_IO. It is a generic error that is not related to SweepMe! but to the use of the VISA runtime which can be used with different programming languages and they all would see the same problem.
Is there any program or service that tries to make a connection via the same port?
If you use the VISA runtime from NI, an application called NI IO Trace is installed on your computer as well. It can be used to log all commands/actions related to communication via the VISA runtime. Also the VI_ERROR_IO will be shown there. Have a look whether something unusual happens beforehand.
Sometimes the energy saving settings of a computer can lead to under-powered usb controllers if the computer changes in to a new energy mode after some time no user interaction. We have seen problems with USB-RS232 adapters that have been solved after changing energy saving settings. It could be that e.g. USBTMC is affected as well.
