4-4 Communication Function Below is each frame format (command). Message Configuration: Query Header (Silent interval) Slave address Function code Error check Data Trailer (Silent interval) 4 •Pre-set numbers ranging from 1 to 32 in each Inverter (slave). (Only the Inverter having the same slave address as the query takes in the corresponding query.) •Broadcasting can be performed by setting the slave address to "0". •Data call or loop-back cannot be performed while broadcasting. Functions •Sends the function command. •The 3G3RX corresponds with the following data formats used in the ModBus. •Specifies the function for the Inverter to perform.
•Below are the function codes supported by the 3G3RX. Function Code •CRC (Cyclic Redundancy Check) is used for the Modbus-RTU error check. •The CRC code is a 16-bit data generated for the block of random length data in the 8-bit unit. •To prepare the CRC code, use a generation polynomial of CRC-16 (X16 + X15 + X2 + 1).
4-155 Data name Description Coil 2-value data (1-bit long) that can be referred to or changed Holding register 16-bit long data that can be referred to or changed Function code Function Maximum number of data bytes in 1 message Maximum data number in 1 message 01h Reading coil status 4 32 coils (in bits) 03h Reading holding register content 8 4 registers (in bytes) 05h Writing into the coil 2 1 coil (in bits) 06h Writing into the holding register 2 1 register (in bytes) 08h Loop-back test 0Fh Writing into multiple coils 4 32 coils (in bits) 10h Writing into multiple registers 8 4 registers (in bytes)