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Data transfer via communication ports
F145F146_MODBUS
_MASTER
Write data from a master to a slave or read data from a slave via the serial port (COM1 or COM2)
Description
depending on the function code. The Modbus RTU protocol (see communication mode (see page
712)) must be set in the system registers (see page 1273). Select "Modbus RTU Master/Slave" for
the desired port.
This instruction is identical to F145F146_MODBUS_COMMAND (see page 777), but it also
supports slave addresses higher than 99 and a wider range for the start register.
In contrast to other F145 or F146 instructions, the required Modbus command can directly be set
by the parameter FunctionCode*.
General programming information for F145 and F146 (see page 766)
Commands supported by the master:
Function
System constant
code
01
SYS_MODBUS_01_READ_COIL
02
SYS_MODBUS_02_READ_INPUT
03
SYS_MODBUS_03_READ_HOLDING_REGISTER
04
SYS_MODBUS_04_READ_INPUT_REGISTERS
5
SYS_MODBUS_05_FORCE_COIL
6
SYS_MODBUS_06_PRESET_REGISTER
15
SYS_MODBUS_15_FORCE_COILS
16
SYS_MODBUS_16_PRESET_REGISTERS
Modbus specifications for Panasonic PLCs:
Reference numbers
From 000001
From 002049
From 100001
From 400001
From 300001
From 302001
For reference number and address area ranges supported by the Panasonic PLCs, please refer to the User's
Manual of the PLC. If the reference number is outside the supported range, an error is returned.
780
Write data to slave or read data from slave
Address area of Panasonic PLCs
From Y0
From R0
From X0
From DT0
From WL0
From LD0
Start register
Number of
registers
0–65535
1–2040
0–65535
1–2040
0–65535
1–127
0–65535
1–127
0–65535
1
0–65535
1
0–65535
2–2040
0–65535
2–127
Reference
numbers
(depending on
Modbus slave)
000001–065536
100001–165536
400001–465536
300001–365536
000001–065536
400001–465536
000001–065536
400001–465536
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