Honeywell HC900 - Fixed Modbus Map; Table 4-2 Maximum Number of Objects (Fixed Map Only)

Modbus/TCP & Modbus RTU Function Codes
Fixed Modbus Map
18 HC900 Process Controller Communications User Guide Revision 13
April 2017
4.2 Fixed Modbus Map
Table 4-2 and Table 4-3 list the the maximum number of Object Addresses and maximum number of registers
allowed per request. Also shown are differences between firmware versions 2.3 and 2.4.
Note 1: In versions 4.0 and higher these maximums apply to fixed map but not to the custom map.
Note 2: In versions 4.0 and higher function code 03 is not available for analog inputs.
Table 4-2 Maximum Number of Objects (fixed map only)
Note: objects marked with * have multiple parameters and therefore occupy multiple registers. For
example, a PID loop has over 40 parameters that can be accessed.
Object Name
Max. No. of Objects
Function Code
C30
C50/C70/C70R
Analog Inputs
96/12 slots v2.3
192/12 slots v2.4
640 v2.3
1280 v2.4
3: can only access first 8 slots
of rack 1. Not available in
version 4.0 or higher.
4: can access all slots and
racks
Discrete Input
192/12 slots v2.3
384/12 slots v2.4
1280 v2.3
2560 v2.4
2
Discrete Output/Coil
192/12 slots v2.3
384/12 slots v2.4
1280 v2.3
2560 v2.4
1: read
5: force
Loop*
8
32
3
Variable Value
600
600
3
Set Point Programmer Value*
8
8
3
Segments per Set Point
Programmer*
50
50
3
Signal tags
2000
2000 (C50)
5000 (C70/C70R)
3
Scheduler Value*
2
2
3
Segments per Schedule*
50
50
3
Sequencer*
4
4
3
Stage*
8
8
3
Ramp*
8
8
3
Hand-Off-Auto*
16
16
3
Alternator*
6
6
3
Device Control*
16
16
3
User Defined Registers
1024
1024
3