We have a Lauer make MMI connected to Siemens S5 PLC. Recently, the MMI failed. We have a spare one and tried to install it in line. Initially we faced the problem of communication with PC using PCS PRO 5.8 software. The communication could not be established. Later it was found that we needed WIN95 OS in PC. The same was done. Now the communication is taking place but still having errors. I wanted to know if anyone had used the same with SIEMENS S5 PLC and has special observations/settings to be done in the communication part for downloading. Can anyone give me a step by step procedure for doing the same...?