11. Connection to other devices
11.4 Modbus TCP
11.4.4 Modbus map
Function code
Modbus
Modbus
reg. #
Operand Description Remark
0x01
(Read Coil)
Max. 512 coils at
once,
8 coils are
grouped into a
byte
1 Q1 Bit output 1 Local outputs base device
… … …
4 Q4 Bit output 4
17 Q17 Expansion
Bit output
Local outputs expansion
… … …
128 Q128 Expansion
Bit output
1001 M1 Marker bit 1
... … …
1512 M512 Marker bit 512
2001 N1 NET marker bit 1 Only the local NET marker bits
are returned
… … …
2512 N512 loc. NET marker bit 512
0x03
(Read Holding
Register)
Max. 125 registers
at once,
1 register =
2 byte/1word
1 QA1 16-bit analog output 1 Local analog outputs base
device
… … …
4 QA4 16-bit analog output 4
5 QA5 Expansion 16-bit analog
output
Local analog outputs expansion
… … …
148 QA48 Expansion 16-bit analog
output
1001 MW1 Marker word 1
… … …
1512 MW512 Marker word 512
2001 NW1 loc. Net marker word 1 Only local NET marker words
will be returned, i.e., no double
words, no bytes, and no mark-
ers from the other stations will
be returned
… … …
2032 NW32 NET marker word 32
5000 RTC (second) 5000: Seconds; 5001: Minutes;
5002: Hours; 5003: Day; 5004:
Month; 5005: Year
…. … …
5005 RTC (year)
Table 105: How the Modbus registers and read data for the Modbus server are mapped easyE4 control relays
easyE4 11/18 MN050009 EN www.eaton.com
557