Hello kboggs,
As PdL points out, the Westermo range has been tested with Omron PLCs, and are extensively documented on the Westermo web site.
If you are (I hope) a registered CX-One user, you can download (for free) Omrons CX-Modem tool.
This was developed with the Westermo modems in mind, and contains the AT command sets for setting up the modems, as well as helping with the connection diagnostics should something be awry.