Honeywell HC900 - I;O Network

Modbus/TCP & Modbus RTU Function Codes
Function Code 04 - Read Input Registers
32 HC900 Process Controller Communications User Guide Revision 13
April 2017
4.6 Function Code 04 - Read Input Registers
Description
Function code 04(3X references) provides read access to Analog Input modules positioned in any Rack or
Slot. All values are in IEEE 32-bit floating point format.
For HC900 CPUs and Scanners with firmware version 2.3 and earlier, each Rack is allocated space for a
maximum of 16 Slots and each Slot assumes Modules with a maximum of 8 Channels, which consumes 16
Modbus Register addresses. See Table 4-9.
For HC900 CPUs and Scanners with firmware version 2.4 and higher, each Rack is allocated space for a
maximum of 16 Slots and each Slot assumes Modules with a maximum of 16 Channels, which consumes 32
Modbus Register addresses. See Table 4-10.
In Table 4-9 and Table 4-10 the register addressing is 1-based while the hex addressing is 0-based.
Table 4-9 HC900 AI Address Mapping supported by Function Code 04 (v2.3)
Rack
Channels
Register Range
(decimal)
Hex
Address Range
1
1 - 128
1 - 255
0 –FE
2
129 - 256
257 - 511
100 - 1FE
3
257 - 384
513 - 767
200 - 2FE
4
385 - 512
769 - 1023
300 - 3FE
5
513 - 640
1025 - 1279
400 - 4FE
Table 4-10 HC900 AI Address Mapping supported by Function Code 04 (v2.4 and higher)
Rack
Channels
Register Range
(decimal)
Hex
Address Range
1
1 – 256
2001 – 2511
0 -9CE
2
257 - 512
2513 – 3023
9D0 – BCE
3
513 - 768
3025 – 3535
BD0 – DCE
4
769 - 1024
3537 – 4047
DD0 – FCE
5
1025 - 1280
4049 - 4559
FD0 – 11CE
6
1281 - 1536
4561 – 5071
11D0 – 13CE
7
1537 - 1792
5073 – 5583
13D0 – 15CE
8
1793 - 2048
5585 – 6095
15D0 – 17CE
9
2049 - 2304
6097 – 6607
17D0 – 19CE
10
2305 - 2560
6609 – 7120
19D0 – 1BCE
11
2561 - 2816
7122 – 7632
1BD0 – 1DCE
12
2817 - 3072
7634 - 8144
1DD0 – 1FCE