In principle such an application is possible by making your own connector and using a standart RS 485/232 converter, but I think that is not practical. TD200 uses PPI protocol, where modem needs freeport mode, therefore when you change communication from TD200 to modem and from modem to TD200, each time you have to modify SMB30 area. This will cause some delay and there is a risk of losing data. Also difficult to program. Can't you use CPU216 or CPU226 which has two ports?
