User`s manual

78
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
8 Master Specification
8.1 MODBUS Master Command List
8. Master Specification
This chapter explains the MODBUS Master functions supported by the FX-Series MODBUS
Communication ADP.
8.1 MODBUS Master Command List
Command
Code
Subcommand
Code
Command Name Details
0x01 Read Coils Read binary (R/W) devices
0x02 Read Discrete Inputs Read binary (RO) devices
0x03 Read Holding Registers Read 16 bit (R/W) register
0x04 Read Input Registers Read 16 bit (RO) register
0x05 Write Single Coil Write single binary device
0x06 Write Single Register Write single 16 bit register device
0x07 Read Exception Status Read 1 byte of vendor specified data
0x08
Diagnosis
0x00 Return Query Data Loop back function
0x01 Restart Communication Option
Restart communication /Remote
Communication Reset
0x02 Return Diagnostic Register Read 16 bit register of vendor specified data
0x03 Change ASCII Input Delimiter Change ASCII mode End of Message character
0x04 Force Listen Only Mode Switch slave to Listen Only Mode
0x0A
Clear Counters and Diagnostic
Register
Clear all counters and the diagnostic registers
0x0B Return Bus Message Count Read number of detected messages
0x0C
Return Bus Communication Error
Count
Read number of detected comm. errors
0x0D Return Bus Exception Error Count
Read number of detected exception
conditions
0x0E Return Slave Message Count Read number of received requests
0x0F Return Slave No Response Count Read "No Response" counter of the slave
0x10 Return Slave NAK Count Read NAK counter of the slave
0x11 Return Slave Busy Count Read "Busy" counter of the slave
0x12
Return Bus Character Overrun
Count
Read "Bus Character Overrun" counter of the
slave
0x0B Get Comm. Event Counter Read comm. event counter
0x0C Get Comm. Event Log Read comm. event log
0x0F Write Multiple Coils Write multiple binary (R/W) devices
0x10 Write Multiple Registers Write multiple 16 bit (R/W) registers
0x11 Report Slave ID Read Slave ID code data
0x16 Mask Write Register
Manipulate slave register with AND Mask /
OR Mask
0x17 Read/Write Multiple Registers Read/Write multiple 16 bit (R/W) registers