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Simple TCP Messaging (STM)

Hi jason,

I'm not an expert, but if I remember right, a tcp/ip connection allows only a short number of opening port, even if you close the port.

By this way, I have changed my vis (regarding tcp/ip connection) in order to open connection only one time and closing only when shutting down the vi.

Another user received the same error (see page 9 in this topic)



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Message 161 of 174

I see a lot of references to RT systems. Is STM not designed for implementation using Windows applications only? 

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Message 162 of 174

No. It works on every LabVIEW platform that supports TCP/IP functionality.

Rolf Kalbermatter
My Blog
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Message 163 of 174


I am trying to use STM to communicate between multiple labview projects. I have two labview projects that run on the same computer due to a fork in our development team. Project 1 sends position data from stepper motors and analog signals from a cDAQ to Project 2. Project 2 reads data from project 1 and also collects data from a cRIO and EtherCat servo motors via STM. Data from Project 1 and Project 2 are compiled on project 2 and sent to project 3 on a separate computer. STM communication works great between project 1 and 2. I get error 56 when attempting to communicate between project 2 and project 3. When I run a standalone STM server, I can communicate with project 3 across the network with no issue, but when the stm server is integrated in project 2, and project 1 is communicating to project 2, it fails to communicate. When project 2 is executed before project 1, it will connect to project 3, but then I can not get project 1 to communicate with project 2.

I am using unique ports for each leg of communication:

Proj 1 - Proj 2 : port 55554

Proj 2 - cRIO : port 55551

Proj 2 - Proj 3 : port 55555

Firewalls are disabled on both computers.

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Message 164 of 174

Hi John

I think you have the same problem that I found in the past... see what Christian had suggested to me (page 16)

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Message 165 of 174

I am using a STM server and client similar to TCP STM Reconnect Example Christian posted on pg  11, and not using the connection manager. STM is not required between project 1 and 2, so I will be changing my approach for transferring data between the two projects.


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Message 166 of 174

hi John,

is it possible to have an example of what you have developed?





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Message 167 of 174



I want to use STM for server-client communication and very new to STM. My use case is:

- Server Project has several modules/VIs that will do data acquisition, all in the same server PC. The data would then be displayed in client(s).


The sample I see so far has only 1 VI to do the STM... Any sample program (server side) for this case?

Thanks & Regards,
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Message 168 of 174

Hi Irfan


I had your same problem two years ago.

Starting from message no. 151, you may find the solution



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Message 169 of 174

Thanks DH.


Do you have an updated version of your original program that you sent?

Based on the message thread, I need to make a copy of several STM library files, one copy per one vi, right?

In my case, I use VI template for Acquisition VI, and there might be N number of DAQ VI running in parallel (the number of vi running can vary depending if they're alive or not).


I saw you're also using vi template. How do you figure out the workaround to make duplicate copy per vi?




Thanks & Regards,
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Message 170 of 174