As a prelude, this issue may likely not be VISA related so much as related to either my physical connections or my misunderstanding of the product datasheet. Any help would be appreciated, but I can also reach out to the manufacturer if needed.
I am trying to command a Varian V-70 Turbo Pump controller from my host Windows 10 PC via a USB to RS232 adapter cable. My software configuration is as follows:
I have tried to communicate with this device in both LabVIEW and in a VISA test panel in NI MAX. In both cases, I get the classic timeout error:
Attached is the manual for the device. Pages 74 and 75 are of interest, as they outline the physical connections and communication setup in software. Below are two relevant snippets:
I have ensured my VISA session is configured with the correct format (baud rate, data and stop bits, parity) and have also tired timeouts of various lengths. In addition, I have followed the manuals instructions for ensuring the controller is in the proper mode to accept commands via RS232. Based on everything I have tried, the questions/thoughts I have are as follows:
Thanks for any help!
Solved! Go to Solution.
A USB-RS232 adapter should be fine in this case. This phrase is just saying that you can use a standard, straight-through serial cable and you don't need a null modem (or crossover) serial cable.
Whether you use a built-in serial port in your computer or the USB adapter, the results should be the same. That being said, I'd always suggest trying another port just as a troubleshooting step to rule out the adapter as the cause of the timeout. You could also try a serial loopback on the adapter just to make sure it is working correctly.
I'm struggling to understand this as well, whether you need to just send the character or need to send the full Request+CRC. You could try both! But I would also say that the manufacturer should be able to give you better explanation about how that commands should be formatted.
I don't believe that VISA will automatically handle the CRC. VISA should just be writing out whatever bytes you specify in the VISA write VI.
USB RAW is used to control USB devices, but in this case the USB to serial adapter should be enumerated on your PC as a COM port. So you only need to communicate with the COM port using VISA and don't have to worry about the USB communication at all.
Thanks for your help, Jordan! I think the next step is try to a bunch of different command configurations and if all else fails contact the manufacturer.