6. Function blocks
6.1 Manufacturer function blocks
Modbus RTU map
If you use a Modbus RTU communication module in slave mode for Modbus RTU com-
munications, a Modbus RTU master will be able to access the following easyE4 base
device registers with read and write operations.
Function code
Modbus
Modbus
reg. #
Operand Description Remark
0x01
(Read Coil, FC1)

0x02
(Read Discrete Input,
FC2)

Max. 512 coils/discrete
inputs at once
8 coils/discrete inputs
are merged into a byte

50001
Q1
Bit output 1
Local outputs
base device
…
…
…
50004
Q4
Bit output 4
   
50017
Q17
Expansion
Bit output 17
Local outputs
expansion
…
…
…
50128
Q128
Expansion
Bit output 128

52001
I1
Bit input 1
Local inputs
base device 
… … 
52008
I8
Bit input 8
   
52017
I17
Expansion
bit input 17
local inputs
expansion
…
…

52128
I128
Expansion
bit input 128

54001
ID1
Diagnostics bit 1
Diagnostics
for base
device
…
…
…
54024
ID24
Diagnostics bit 24
   
54025
ID25
Diagnostics bit 25
Expansion
diagnostics
...
...
…
54096
ID96
Diagnostics bit 96

56001
M1
Marker bit 1

...
…
…
56512
M512
Marker bit 512

58001
N1
NET marker bit 1
Only the local
NET marker
bits and no
marker bits of
the other sta-
tions are
returned
…
…
…
58512
N512
loc. NET marker bit 512
Tab. 86: Modbus registers and read data for the easyE4 control relay Modbus slave
easyE402/24 MN050009ENEaton.com
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