10
Figure 4
– Modbus Diagnostic LEDs
C. MODBUS COMMUNICATION
The Modbus communication commands can be found in Parts 3 and 4 of this manual, and exception codes supported by the
communication board can be found in Part 5, Section E.
D. MODBUS FUNCTION SET
FUNCTION
SUB FUNCTION
HEX
DESCRIPTION
DEC
HEX
DEC
1
01
Read coil status
2
02
Read input status
3
03
Read holding registers
4
04
Read input registers
5
05
Force single coil
6
06
Preset single register
7
07
Read exception status
8
08
0
00
Diagnostic
– Return query data
1
01
Diagnostic
– Restart communication
2
02
Diagnostic
– Return diagnostic register
4
04
Diagnostic
– Force listen mode
10
0A
Diagnostic
– Clear counters and diagnostic registers
11
0B
Diagnostic
– Return bus message count
12
0C
Diagnostic
– Return bus exception error count
13
0D
Diagnostic
– Bus exception error count
14
0E
Diagnostic
– Return follower message count
15
0F
Diagnostic
– Return communication error count
16
10
Diagnostic
– Return follower NAK count