LabVIEW STM API not working with cRIO when web app services are disabled

[StevenHowell]

Good evening.

I have an application running on an NI cRIO-9057 that is controlling an environmental system.

I need the ability to have multi connections to the server (RT App) simultaneously. Due to the ease of use I chose initially to work with the STM API that was developed by NI Systems Engineering some years ago. It has been working perfectly until now.

Recently we have had to start securing web services running on our controls platforms and I was asked to turn off the application web server and system web server on the cRIO target.

After doing this, I was unable to connect using the User Interface that has the STM API embedded in it. 

I went back to the cRIO platform and re-enabled the default web services and it worked again. 

Not sure why a TCP VI would need the web services to be on? Am I missing something?

Thanks in Advance,

-Steven

[santo_13]

Check out this article to learn more about STM - https://forums.ni.com/t5/Reference-Design-Content/Simple-Messaging-STM-Communication-Library/ta-p/34...

[StevenHowell · Accepted solution]

Thanks for the links, unfortunately they were not able to provide much information.

As it turns out, if I have the web server turned off on the target, whatever port I assign as the listener port, that port is never opened when the target reboots.

For whatever reason, the web services have to be on for the listener port on the TCP palette to open.