USB to RS-485 Communication Problems

[JasonSmith]

Which version of NI-Serial are you using? NI-Serial 3.4 resolved some speed problems that existing with NI USB Serial hardware, so if you have not upgraded I would recommend that you try that.

-Jason S.

[JasonSmith]

If you are already using NI-Serial 3.4 and still having issues, you could try obtaining a capture of what is happening with Microsoft Portmon. This attaches at the driver level instead of the NI-VISA level, so it should be able to capture your activity even though you are using it through a third party application that is not using NI-VISA.

It would be really helpful if you could pick a short operation that you can perform with both the PCI board and the USB adapater. We could then try to see what is happening differently when you are using the USB hardware. For this to work you will need to make sure that you are doing the exact same operation with both pieces of hardware--preferably something that will demonstrate the performance problem without creating too long of a capture file.

-Jason S.

[MWJ]

Jason,

I'm using the current version of teh software which apperas to be 3.4

MWJ

[1967]

i have pci1110 card from eliwell which convert rs 232 to rs 485 to communcat with televis system eliwell can i replace with rs usb to rs 232 and rs 232 to rs 485 unversail

thanks

s. e .m

[David_Pratt]

Is there any reason why you wouldn't want to just buy a USB-485 cable?  This would eliminate a possible point of failure in your system.  To answer your initial question, yes, the system would work by connecting a USB-232 and then a 232-485 adapter.