Modbus Communication, Adding shared variables, Licenses

[schoo032]

Hello,  I am having trouble communicating with a third party DAQ.  I am receiving data from a thermocouple input module through a modbus library address but I recently purchased a digital I/O module which is giving me trouble.  As soon as I add the shared variables which correspond to the modbus addresses of the digital I/O module channels I am using I get a few different errors.  If I turn off aliasing for one of the thermocouple channels I get Error 1550 "the license for the I/O server type is invalid"....If I turn it back on I get errors for every modbus location saying "invalid value for enable aliasing option"  I am using the student edition and on the opening screen it says the data logging license is expired.  Is that the problem?  I don't think so because I am successfully communicating with the thermocouple module of the same DAQ device.  Is there a simple way to write a new VI that I can try to communicate with just a switch on the digital I/O module and see if it is reading on or off (0 or 1).  Thank you very much for your time

[Jesse_D]

Hi schoo, 

Screenshots of the behavior you are seeing would be helpful. 

You can check in the license manager  located at Start>>All Programs>>National Instruments>>License Manager. Look for the Datalogging and Supervisory Control Module to be green. 

Depending on how you are communicating with the daq device, aside from modbus, you may not be using the DSC module. If the DSC module is activated can you create give me screen shots of the behavior you are seeing? 

[brade034]

Jesse, Schoo and I are working on this project together. The license you specified below is out of date. Is that necessary to run the program? Attached is a screenshot of the error we're getting.

[Jesse_D]

Hi Brade, 

That isn't a licensing error, it is a deployment error. I had a similar discussion with a person here that might help you. Basically, something is wrong with the way you have the modbus variables configured. There is a checkbox you need to uncheck. 

Read through the thread and let me know if you can find the checkbox. If not I will post screenshots. 

[brade034]

Ok, I went through the other thread you suggested and couldn't find the check box. Could you send a screenshot? Thanks for the help!

[Jesse_D]

Hi brade, 

To clarify where we are at. the behavior you are seeing isn't expected. It is a minor bug that we have seen in R&D but haven't been able to reproduce and fix yet. 

People have gotten around it by

1) re-making their projects 

2) Enabling descriptions, as the engineer in other post.  The problem went away for him on this post: "Aliasing is no longer an error.  (As long as NI Variables (task description) is enabled)."

We were talking about the aliasing tab you can see on the modbus variables in hte labview project by right-clicking and going to properties; 

I assume he checked the box on this tab: 

Can you also post your project? 

[brade034]

ohhh, ok. I found that before but wasn't sure if that's what he was talking about. Alright, I unchecked them, but im still getting an I/O server license error. It's attached below.

Not sure if I can post the project, ill check on that. Thanks!

[Jesse_D]

Hi Brade, 

That is back to a licensing issue. The fact the DSC license is expired is probably your problem. You can either try activating the DSC module in the license manager with your student serial number, or if that doesn't work download a trial version of the DSC module. You also can try the free modbus library.

If none of these steps work you may need to get another software license for the DSC.