You can connect a modem via the Panel USB Host port, or via a UniCom module with a RS232 port.

Configuring ports

– Panel USB port: connect the modem to the USB port via a USB to serial converter. The supporting UniStream driver is PL2303, which is compatible with most USB to Serial converters.
In the Solution Explorer, click PLC Communication > Physical >Panel USB Port to open the Properties Window, and then select Enable USB for Serial Device. Next, open the Panel USB Port Settings, click the Initialize Port for: options and then select Modem.
(Vision users: please note that no ‘Prepare PLC-side modem’ procedure is required.)
– RS232 module (ex. UAC-01RS2):
Include the UniCom module in your Hardware Configuration: in the Solution Explorer, click Hardware Configuration> Local I/O and COM Modules and add the COM module.
Then, in the Properties Window, open Com Port Settings> Initialize Port for: Options and select Modem
To link a port to the modem: click Solution Explorer > Modems, and click Communication Channel. A drop-down list will display the available ports; click one to select it.