RIEVTECH STUDIO SOFTWARE MANUAL There are 2 available options for Rievtech PLCs, one is FBD mode(programming mode is Function block diagram), another is LAD mode(programming mode is Ladder) If your PLC program is FBD, you need select (RS232 or RS485 communication) or (Ethernet communication) as the device model. And the register address configuration is the modbus address. Modbus address is listed in below: For example, if you want to read I1 status, you need select register type “ I ” , address is 0. And if you want to read AF1 value, you need select register type “ AF ” , address is 3072. 24