We finally got to the bottom of the issue. Here’s the summary:
In order to test the connection, we tried running the following command line from the Ignition Server:
telnet IP 102
where IP is the PLC’s IP address and 102 is the standard port used to communicate with the SIMATIC S7-400 PLCs. If an error is returned, then this means that the Ignition server is not able to communicate with that IP address via port 102.
We had to contact the Network Administrator, who opened the communications via port 102 for us, after which all started working.
It’s interesting to note, that prior to that, there were no messages being displayed under Status->Diagnostics->Logs. Only after the networking issue was resolved, we starting seeing messages in the Logs section.
Port 102 is the default to communicate with SIMATIC S7-400 PLCs. These ports are fixed, and there is no way to configure them otherwise. For more information, please refer to the following link:
Thanks for helping.