I would like to establish a serial connection from a PC to a remotely located data logger. The TRB142 (firmware TRB1_R_00.07.01.2) provides the serial port in the field, and on the controlling PC a virtual COM port with TCP/IP socket is set up with hub4com/com0com (https://sourceforge.net/projects/com0com/files/hub4com/).
The RS232 port on the TRB142 is configured as Over IP, Protocol: TCP, Mode: Client, Port: xyz, Reconnect Interval: 10s
This works very well at first and I can control and read out the data logger from the PC.
After some time the connection breaks, and with some effort I found the cause: The TRB142 establishes new TCP connections in regular intervals!
You can follow this well with the port monitor CurrPorts, see screenshot. First the communication works (you can see this in the second line, Sent/Received Bytes). Then in intervals of about 30 minutes (with further attempts it was also 12 minutes) new TCP connections are established, a communication is no longer possible.
If you delete the older existing TCP connections except the current one manually with CurrPorts, you can communicate again, until the TRB142 establishes an additional TCP connection again. Or you restart hub4com each time.
What can be done to prevent this behavior? The cause seems to be the TRB142 alone, the multiple connections happen without anything being connected to its RS232 port.