Modbus Registers - Honeywell IAQPoint2 Technical Manual

Modbus registers

Some models of the IAQPoint2 contain a digital interface for communicating
over RS-485 networks� This interface can be switched in software to use either
the Modbus RTU or BACnet MS/TP protocols� It can communicate at any speed
from 4800 to 115,200 baud� When configured for Modbus and 9600 baud, the
IAQPoint2 is compatible with the Honeywell 301C controller� The IAQPoint2 can
directly replace an IAQPoint1 in Modbus or analog applications�
More information on Modbus can be obtained at www�modbus�org� The
IAQPoint2 contains 12 Modbus holding registers� hese are numbered from
40101 to 40112 – it skips over the first 100� There are no input registers, output
registers, or coils� Holding registers 40101 provides a concise summary of
essential status� Two holding registers are writable via command 06�
This flowchart includes fieldbus and simulation features�
-
Gas Sensor Value
Screen Configure / Configure
+
Setpoints / Set Gas Setpoint
BACnet object GAS_SPT_AV
Gas Sensor Fault
Modbus Hld Reg 40105
Screen Configure / Configure
Setpoints / Set Gas Hyst
Home Screen
'Occ' softkey
Figure 23. IAQPoint2 relay flow with fieldbus and simulation elements
BACnet object GAS_RDG_AI
Modbus Hld Reg 40102
Modbus Hld Reg 40101b3
and
not
BACnet object RLY_DRV_BO
Modbus Hld Reg 40112
Screen Configure / Configure
Output / Set Occupied Timeout
Countdown
reset Q
Timer
BACnet object OCC_DRV_BO
Modbus Hld Reg 40111
BACnet object IAQGOOD_BI
Screen Configure / Configure Outputs Screen Simulate
/ Set Relay
Gas Conc. Max (on)
Fieldbus Normal
Occ Tmr Min (off)
BACnet object OVDTIMER_BI
Modbus Hld Reg 40101b12
"Occupied"
or
icon
IAQPoint2
Relay
Coil
51