288 MODBUS – CODESYS 2
WAGO-I/O-SYSTEM 750
750-8207 PFC200 CS 2ETH RS 3G
Manual
Draft version 1.2.1 from 2017-09-13, valid from FW Version 02.06.20(09)
10.4.4.3 MODBUS Mapping for Read Register Services FC3, FC4, FC23
The table below outlines the mapping for the MODBUS-reading, register-oriented
services:
•
FC3 – Read Holding Registers,
•
FC4 – Read Input Registers,
•
FC23 – Read/Write Multiple Registers
Table 208: MODBUS Mapping for Read Register Services FC3, FC4, FC23
MODBUS Address
(hexadecimal values
in parentheses)
IEC 61131
Address
Description
0 … 999
(0x0000 … 0x03E7)
%IW1000 …
%IW1999
MODBUS Output:
1000 PFC input registers/words in the
2 kB MODBUS output process image in
the PII.
Note: In this area, the read register
services return the content from the PII.
1000 … 1999
(0x03E8 … 0x07CF)
%QW1000 …
%QW1999
MODBUS Input:
1000 PFC output registers/words in the
2 kB MODBUS input process image in
the PIO.
Note on FC23:
Only the Read portion of this service can
be executed.
2000 … 4095
(0x07D0 … 0x0FFF)
Inhibited to MODBUS-only area for
register-oriented read access. Register-
based read services for this area are
acknowledged by the MODBUS slave
with the MODBUS exception code
“ILLEGAL DATA ADDRESS” (0x02).
4096 … 12287
(0x1000 … 0x2FFF)
No IEC 61131
address
Information and configuration registers:
Not all MODBUS addresses in this range
are valid.
Valid MODBUS addresses are described
in the Section “WAGO MODBUS
Registers”.
Access to invalid addresses are
acknowledged by the MODBUS slave
with the MODBUS exception code
“ILLEGAL DATA ADDRESS” (0x02).
Note on FC23:
The Write portion of this service can only
be executed for registers that data can
be written to.
