Modbus Standard Functions; Modbus Standard Function Support List - Mitsubishi Electric QJ71MT91 User Manual

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MODBUS STANDARD FUNCTIONS

4 MODBUS STANDARD FUNCTIONS
This chapter explains the MODBUS standard functions supported by the QJ71MT91.

4.1 MODBUS Standard Function Support List

(1) MODBUS standard function support list
Function Code
(Sub Code)
01 Read coils
02 Read discrete inputs
03 Read holding registers
04 Read input registers
05 Write single coil
06 Write single register
07 1 2 Read exception status
08 1 2 Diagnostics
Get communications event
11 1 2
counter
12 1 2 Get communications event log
15 Write multiple coils
16 Write multiple registers
17 1 2 Report slave I.D
20(6) Read file record
21(6) Write file record
22 Mask write register
23 Read/write multiple registers
24 1 Read FIFO queue
43 1 Read device identification
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The following table indicates a list of the MODBUS standard functions supported
by the QJ71MT91.
Function
Reads the statuses (ON/OFF) of one or more coils.
Reads the statuses (ON/OFF) of one or more inputs.
Reads the values of one or more holding registers.
Reads the values of one or more input registers.
Writes a value (ON/OFF) to one coil.
Writes a value to one holding register.
Reads error statuses indicated by eight coils.
Executes various diagnostics.
The diagnostics results are returned to the master.
Gets the communication event counter.
Gets the communication event log.
Writes values (ON/OFF) to multiple coils.
Writes values to multiple holding registers.
Reads the information such as the type, status of the slave
device to the master.
Reads the values of one or more extended file registers.
Writes values to one or more extended file registers.
Masks the value stored in one holding register with AND or
OR, and writes a value.
Reads and writes values from and to multiple holding
registers.
Reads values from the holding registers in FIFO queue
structure.
Reads the module identification information of the slave.
1: The QJ71MT91 slave function does not support this function.
However, it can be issued from the master (QJ71MT91) by use of the MBREQ instruction.
2: The function codes 07, 08, 11, 12 and 17 are the functions dedicated to the MODBUS serial
protocol.
Processing
MELSEC-Q
Reference
Section 4.3.1
Section 4.3.2
Section 4.3.3
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Section 4.3.4
Section 4.3.5
Section 4.3.6
Section 4.3.7
Section 4.3.8
Section 4.3.9
Section 4.3.10
Section 4.3.11
Section 4.3.12
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