There are two ways: 1. there is a modem wizard included in the newer versions of Microwin32 (V3.1 and 3.2) but you still need to fill up some modem details in it; 2. try to include EM241 (modem expansion module) to your CPU226 and then follow the EM241 wizard in the V3.2. Read first the manual...
I had experienced this kind of problem before, I used a SIEMENS SIMATIC S7-300 with analog input module. The good thing with my project was that errors were not that important. I just evaluated the values read by the CPU from the FT and totalized it using continues addition (since flow is...