Serial Interface (Modbus RTU)140 M-Max Series Adjustable Frequency Drive MN04020003E—October 2013 www.eaton.comExplanation of Function CodeFunction Code 03 (hex): Reading of Holding RegistersThis function reads the content of a number of consecutiveholding registers (of specified register addresses).Example:Reading of motor speed (ID 2105) and motor current (ID2106) of the M-Max frequency inverter with the slaveaddress 5.Master request: 05 03 0838 0002 4622 (hex)Slave response: 05 03 04 05D7 0018 0F0D (hex)Function Code 04 (hex): Reading of Input RegistersThis function reads the content of a number of consecutiveinput registers (of specified register addresses).Example:Reading of motor speed (ID 2105) and motor current (ID2106) of the M-Max frequency inverter with the slaveaddress 5.Master request: 05 04 0838 0002 F3E2 (hex)Slave response: 05 04 04 05D7 0018 0EBA (hex)Hex Name05 Slave address03 Function code (reading of holding registers)0838 2104 (dec): The ID number of the first requestedregister is 2105 (dec) as the master PLC has anoffset of +1.0002 Total number of requested registers(42105–42106)4622 CRCHex Name05 Slave address03 Function code (reading of holding registers)04 Number of consecutive data bytes(2 registers x 2 bytes = 4 bytes)05D7 Content (2 bytes) of register 42105: 1495 (dec)(motor speed = 1495 RPM)0018 Content (2 bytes) of register 42106: 0024 (dec)(motor current = 0.24A)0F0D CRCHex Name05 Slave address04 Function code (here: Reading of input registers)0838 2104 (dec): The ID number of the first requestedregister is 2105 (dec) as the master PLC has anoffset of +1.0002 Total number of requested registers(32105–32106)F3E2 CRCHex Name05 Slave address04 Function code (here: Reading of input registers)04 Number of consecutive data bytes(2 registers x 2 bytes = 4 bytes)05D7 Content (2 bytes) of register 32105: 1495 (dec)(motor speed = 1495 RPM)0018 Content (2 bytes) of registers 32106: 0024 (dec)(motor current = 0.24A)0EBA CRC
