Hello, We have a problem with Unitronics Jazz 2 series PLCs (JZ20-R31, +adapters MJ20-RS) trying to connect to modbus communication line. The problem is we cant initializate RS-485 com port, every configuration are restored to factory default (9600;7;1;even;n) after RS-485 cable connection to PLC and in system menu it is impossible to change communication parameters if RS-485 cable is connected (RS-232 com port we do not use). We do not have any problems with Jazz 1 series plcs using almost same program, same configuration. + U90 ladder we are using last version (v6.4.9) + Unitronics 2 series OS is last version (V2.30 (B08)) + Communication line is good (we checked). + We have two Jazz 2 series plcs with same problem. P.S sorry for my english.