12
4
ModBus Memory Map
ModBus and BACnet Communication Instructions
Input Registers
Address
Description
Default
Unit
Min.
Max.
Resolution
30001
Discrete Inputs 1 - 16
0
HEX
0
65535
1
30002
Discrete Inputs 17 - 32
0
HEX
0
65535
1
30003
Discrete Inputs 33 - 48
0
HEX
0
65535
1
30004
System / Cascade Setpoint
0
Degrees Celsius
0
130
0,5
30005
System Pump Speed
0
%
0
100
1
30006
Cascade Total Power
0
%
100
800
1
30007
Cascade Current Power
0
%
0
800
1
30008
Outlet Setpoint
0
Degrees Celsius
0
130
0,5
30009
Outlet Temperature
0
Degrees Celsius
0
130
0,1
30010
Inlet Temperature
0
Degrees Celsius
-20
130
0,1
30011
Flue Temperature
0
Degrees Celsius
-20
130
0,1
30012
Firing Rate
0
%
0
100
1
30013
Boiler Pump Speed
0
%
0
100
1
30014
Boiler Status Code
0
HEX
0
65535
1
30015
Boiler Blocking Code
0
HEX
0
65535
1
30016
Boiler Lockout Code
0
HEX
0
65535
1
Holding Registers
40001
Con
fi
guration
0
NA
0
65535
1
40002
Coils
0
NA
0
65535
1
40003
0-10 Volt Input / Rate Command / Setpoint
Command
0
%
0
100
1
40004
Tank Setpoint
0
Degrees Celsius
0
87,5
0,5
40005
Tank Temperature
0
Degrees Celsius
-20
130
0,1
40006
Outdoor Temperature
0
Degrees Celsius
-40
60
0,1
40007
System Supply Temperature
0
Degrees Celsius
-20
130
0,1
40008
DHW Recirculation Temperature
0
Degrees Celsius
-20
130
0,1
Memory Map
Con
fi
guration Bits
Address 40001 contains confi guration bits sent from the BAS to the appliance. Th
ese bits tell the boiler/water heater to use its
own internal inputs, or inputs from the BAS. When a bit is set to 1, the boiler/water heater will ignore the corresponding value
contained internally, and expect the BAS to write that value into the Holding Registers. Th
e confi guration bits are as follows:
Bit 4: System Supply Temperature
Bit 5: Outdoor Temperature
Bit 6: Tank Temperature
Bit 7: System Return Temperature
Bit 8 - 15: Not Used (Default = 0)
Bit 0 (LSB): Boiler Enable
Bit 1: Tank Th
ermostat
Bit 2: Rate Command / 10 - 10V Input / Setpoint Command
Bit 3: Tank Setpoint
