Problem with Prologix GPIB-USB - Page 1
Forum section: electronics / beginners

author: kenarton
author_rank: Newbie
timestamp: March 19, 2021, 10:40:32 pm
content: Hello,This is my first post on this forum.I'm not a beginner, but not being sure of best place, I decided just to put thepost here. I hope that's OK.I have a Prologix GPIB-USB controller that I bought years ago, and used brieflyto control an HP6622A power supply. I got it working, but then set that project aside,as it all seemed a bit complicated at the time and I had other things to do.I now have a lot more experience, and want to get it going again, but have run into aproblem with the Prologix GPIB-USB controller.First, I am on Windows 10 Home, 64 bit,and I am using Cool Term terminal emulator.With everything connected and the HP6622A powered up and using Device Manager I can see the USB Serial Port for the Prologix (COM10 on my PC), Checking on its properties, it says the device is working properly. I have also clicked on Update Driver, and after searching it reports that device drivers are up-to-date.I open Cool Term, and select port COM10, but I do not adjust any of the Serial Port Options since the Prologix guide says they do not matter and may be set to any value.I open the Send String panel, and type in ++mode and click Send.This ought to return the present mode, 0 or 1. But what I get is "??" (five question marks, without the quote marks. I don't know why it puts an emoticon in there)If I try ++addr it ought to return "5", the HP6622 address, but I get "??Y???"Other commands I've tried are similarly useless.It was working in the past, but now something is clearly amiss, probably an elementary step or setting that I've forgotten since I last used it.So I am stuck.Any advice would be much appreciated.Many thanks, Ken

author: JXL
author_rank: Regular Contributor
timestamp: March 20, 2021, 05:57:57 am
content: It appears you may be using the wrong baud rate.● Port: Select virtual COM port created by USB driver● Baud rate: 115200● Data: 8 bit● Parity: none● Stop: 1 bit● Flow control: HardwareType "++ver" <enter> to check if serial communication is working.Good luck!

author: kenarton
author_rank: Newbie
timestamp: March 20, 2021, 11:21:43 am
content: Hi JXL,Thanks for reply.I have set baud rate to 115200, and other port settings as you suggest.Flow control does not offer Hardware, but 3 options instead: CTS, DTR, XONI have tried with each of these in turn.But result is exactly as before.When I send "++ver" it returns: ??10 c/r ?So, still stuck. Ken.

author: kenarton
author_rank: Newbie
timestamp: March 21, 2021, 03:48:01 pm
content: Problem has resolved itself!I tried again this morning.On sending command, eg ++ver, the response was nothing at all.I moved the USB connection to another port, but still assigned as COM10.This time it responded correctly.Moved connection back to original port.And now it also responds correctly on this port!.So all now working as it should.Apart from moving USB connection, I have not changed anything, so haveno idea at all why it was not working before -- very strange; I don't supposeI will ever know. Maybe the problem was with Cool Term.Anyway, I will now close this thread.Thanks all.