Connecting to PLC with GX440 Verizon LTE

When it comes to networking, I’m a little shaky.

I’ve got a pretty basic setup. One PLC & One HMI connected to a Sierra GX440 Verizon/LTE in the field. The Sierra has been set up with static IP from Verizon and I have connected to the Sierra’s AceManager over the internet hitting that static IP…

My PLC and HMI are on a 10.10.10.XXX network with Subnet.

What do I need to configure in the GX440 to allow me to connect to the PLC remotely? Also, does my PLC gateway need to be the IP of the GX440?


I’m glad I’m not the only one who is finding these modems incapable of doing a simple serial to IP passthrough.

We’ve not had any problems connecting a PLC device to this modem, either via the serial port or the ethernet port. If you are connecting via serial port, make sure you configure the Serial tab correctly. You can check to make sure the serial port is open by using telnet (seems easiest). If connecting via ethernet, the modem has its own internal ip addresses (unless you changed them manually). To get to devices behind the modem, go to the Security tab and configure Port Forwarding. Worked for us.

To get in line with the PLC What IP used the Modem or the PLC itself ?.
What ports in your case opened to communicate put the PLC and the HMI?

Do you mean for the serial port? It’s the public IP address of the modem with the port number of the serial port. I believe it’s defaulted to 12345.