Table 4-6 Di/Do Address Map (Firmware Version 2.3 And Earlier, 16 Channels Max); Table 4-7 Rack #1 Di/Do Address Map (V2.3 And Earlier, Up To 16-Channel) - Honeywell HC900 User Manual

Modbus/TCP & Modbus RTU Function Codes
Function Code 01 – Read Digital Output Status

Table 4-6 DI/DO Address Map (Firmware version 2.3 and earlier, 16 channels max)

Rack
1*
2
3
4
5
*See Table 4-7 for detailed addresses of Rack #1
The coil (register) number for a digital I/O is based on the DI/DO's position in the card cage. It is
determined from the formula:
Coil (register) Number = [(Rack-1)*256] + [(Slot-1)*16] + channel in module
Example: To monitor a coil (register) located in the 2nd channel of slot 10 of rack 3, the Modbus coil
(register) number is:
[(3-1)*256] + [(10-1)*16] + 2 = 658
Some third party software packages will require the 1-based coil/register number to be used for the address
while others will require the 0-based hex address.

Table 4-7 Rack #1 DI/DO address map (v2.3 and earlier, up to 16-channel)

Slot 1
CH# Coil/
register
16 16
15 15
14 14
13 13
12 12
11 11
10 10
9 9
8 8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
26
Channels Coil number/
Register number
1 - 256
257 - 512
513 - 768
769 - 1024
1025 - 1280 1025 - 1280
Slot 2
Addr. CH# Coil/ Addr.
Hex register
0F 16 32
0E 15 31
0D 14 30
0C 13 29
0B 12 28
0A 11 27
9 10 26
8 9 25
7 8 24
6 7 23
5 6 22
4 5 21
3 4 20
2 3 19
1 2 18
0 1 17
HC900 Process Controller Communications User Guide
Address Range
1 – 256
257 - 512
513 – 768
769 – 1024
Slot 3
CH# Coil/
Hex register
1F 16 48
1E 15 47
1D 14 46
1C 13 45
1B 12 44
1A 11 43
19 10 42
18 9 41
17 8 40
16 7 39
15 6 38
14 5 37
13 4 36
12 3 35
11 2 34
10 1 33
Modbus Hex
0 - FF
100 - 1FF
200 - 2FF
300 - 3FF
400 - 4FF
Slot 4
Addr. CH# Coil/
Hex register
2F 16 64
2E 15 63
2D 14 62
2C 13 61
2B 12 60
2A 11 59
29 10 58
28 9 57
27 8 56
26 7 55
25 6 54
24 5 53
23 4 52
22 3 51
21 2 50
20 1 49
Addr.
Hex
3F
3E
3D
3C
3B
3A
39
38
37
36
35
34
33
32
31
30
Revision 13
April 2017