Mitsubishi QJ71MT91, User Manual

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MELSEC-Q
4 MODBUS
R
STANDARD FUNCTIONS
4 MODBUS
R
STANDARD FUNCTIONS
This chapter explains the MODBUS
R
standard functions supported by the QJ71MT91.
4.1 MODBUS
R
Standard Function Support List
(1) MODBUS
R
standard function support list
The following table indicates a list of the MODBUS
R
standard functions
supported by the QJ71MT91.
Function Code
(Sub Code)
Function Processing Reference
01 Read coils Reads the statuses (ON/OFF) of one or more coils. Section 4.3.1
02 Read discrete inputs Reads the statuses (ON/OFF) of one or more inputs. Section 4.3.2
03 Read holding registers Reads the values of one or more holding registers. Section 4.3.3
04 Read input registers Reads the values of one or more input registers. Section 4.3.4
05 Write single coil Writes a value (ON/OFF) to one coil. Section 4.3.5
06 Write single register Writes a value to one holding register. Section 4.3.6
07 1 2 Read exception status Reads error statuses indicated by eight coils.
08 1 2 Diagnostics
Executes various diagnostics.
The diagnostics results are returned to the master.
11 1 2
Get communications event
counter
Gets the communication event counter.
12 1 2 Get communications event log Gets the communication event log.
15 Write multiple coils Writes values (ON/OFF) to multiple coils. Section 4.3.7
16 Write multiple registers Writes values to multiple holding registers. Section 4.3.8
17 1 2 Report slave I.D Reads the type, status, etc. of the slave device to the master.
20(6) Read file record Reads the values of one or more extended file registers. Section 4.3.9
21(6) Write file record Writes values to one or more extended file registers. Section 4.3.10
22 Mask write register
Masks the value stored in one holding register with AND or
OR, and writes a value.
Section 4.3.11
23 Read/write multiple registers
Reads and writes values from and to multiple holding
registers.
Section 4.3.12
24 1 Read FIFO queue
Reads values from the holding registers in FIFO queue
structure.
43 1 Read device identification 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 R serial
protocol.
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