It's important to know what model you have before upgrading the firmware and/or contacting technical support.
Looking at the label on the bottom of the unit is the easiest way to determine if it's the "standard" (RS-232 only) model, or the MEI (RS-232/422/485) model. If that's not feasible, for example, if the unit is located at a remote site, you can
telnet into the PortServer and issue the following command:show version
A PortServer TS 2 (RS-232 only) will look like this:
A PortServer TS 4 (RS-232 only) will look like this:
Running 82000716A PortServer TS 2/4 MEI will look like this:
May 15, 2019