RMX-412x on LabVIEW Real-Time via USB?

[NathanJD]

Since the PXIe-8880 (Phar Lap) doesn't have a built-in RS232 port, I was hoping that I'd be able to control the NI RMX-4124 power supply via the USB interface from LabVIEW Real-Time.  I plugged it into one of the USB 2.0 ports and it shows up in MAX with a USB symbol (with the same name as when I had it in my Windows® PC) but I'm unable to use it successfully.  "InitiaIize.vi" seems to execute without an error but I get error -1073807339 in "Configure Output.vi" (called immediately after Initialize).

Is it possible that I'm just doing something wrong or is this not supported in NI Real-Time?

[JacobJC]

Hi Nathan,

It should be possible depending on how that USB device in being identified. You will need to ensure that NI-488.2, NI-Serial and NI-VISA are installed on your Real-Time target before utilizing VISA commands. Depending on what these VIs are calling, you may need one or all of these drivers installed on the PXIe-8880. Please refer to these two Knowledge Base articles for instruction on how to do this:

Control a USB Device with NI-VISA on a Real-Time Controller

How Can I Test Communication With GPIB Instruments Connected to My Real-Time Target?

Also, here is a Knowledge Base article that explains the Error -1073807339 you are getting. There are many reasons why this error can occur but many times the cause is missing drivers as described in the articles above.

[NathanJD]

Originally, I had both NI-VISA 17.5.0 and NI-Serial RT 17.0.0 when I tested this.  So, after your post I installed NI-488.2 17.6.0 to see if that would help.  Unfortunately, this did not help and I still get the same error in the same location.

When I probe the "Interface Type" property node value of the VISA session in "Initialize.vi", I get 7 which is "USB" (the same value that I get when on Windows®).

P.S.  I'm using LabVIEW 2017 SP1 with this library (http://www.ni.com/download/rmx-412x-power-supplies-driver-1.0/6495/en/) from NI.

[JacobJC]

Hi Nathan,

I would recommend going through the rest of the troubleshooting steps listed in the Error -1073807339 article. Since this is a timeout error, there could be many issues going on with VISA. 1) The device may not understand what commands are being sent to it 2) The port communication settings may not be configured correctly or 3) There could be large delays between commands being sent and received from the device causing a timeout.

The other troubleshooting steps can address these concerns. You can verify communication from your power supply and your RT target following this article.

On top of that, I would try disconnecting and reconnecting the USB connection and also try connecting to the other port. Also try restarting your power supply and PXIe controller.

[WillsHuang]

Hello Nathan, do you have solution for this problem, I also meet the similar problem like you, I try to control RMX 4120 on NI Linux RT via RS232, the problem is when I send IDN?, I cannot get the right response from RMX 4120, I have check the baud rate, stop bit, data bits are all right. If you have solved your problem, can you share the solution with me, thanks in advance.

Hardware: PXIe-8881

Software: VISA 21.0, 488.2 21.0, Serial 21.3 are all installed 

[NathanJD]

I didn't end up controlling it from the PXI.  I'm currently controlling it from Windows®.