Same models different instruments, no consistency.

[Potticary]

I have just started running a lab with 4 big magnets run by 4 Lakeshore 648 power supplies. I want to have 4 graphs showing the last hour of current output for each magnet.

These are USB but install as virtual COM ports. Once connected, windows (7) finds the driver and installs it (seemingly) fine and I can communicate with each via VISA interactive control. However, 2 of them take a second press of the 'query' button before the read is printed...the other 2 work first time. The vi I've set up works fine for the latter 2 but errors out once I connect the former 2 and it's driving me crazy. All 4 look the same in windows device manager with the same drivers and are set up the same in the hardware end (there really aren't that many options anyway).

Basically with the same vi, 2 of the machines work fine and the other 2 do not. I've tried swapping the USB ports and cables to no avail. They were all delivered at the same time so there is not any version or firmware differences.

Anyone can shed some light on this, I would be eternally grateful.

[mferguss]

Hi Potticary,

For me to better understand the setup it would be great if you could post any information regarding the setup. Any screenshots of the query etc. are always appreciated.

The VI you have setup; Is this to query all of the devices or simply one at a time? Posting the VI would be useful.

You mention you are receiving an error? What is this error? Again a screenshot would be useful.

Kind Regards

Matt Fergusson AE UK

[Potticary · Accepted solution]

Hi Matt,

Thanks for your reply. It was a communication error stopping the reading of the data from the machine. After a night of trying to unpick the issue, it turns out that the ports were setup differently in NIMax (Baud rate, parity, etc.). As the ports were apparently set up right in windows device manager, I assumed it carried across into LV.

Once I set them all up correctly, they are now working as intended.

Potticary