7
Primary Data Tables
Table
Data Type
Read / Write
Discrete Inputs
Single Bit
Read Only
Coils
Single Bit
Read / Write
Input Registers
16-Bit Word
Read Only
Holding Registers
16 Bit Word
Read / Write
Crest Boiler Memory Map
Coils
Address
Description
Default
Unit
Min.
Max.
Resolution
00001
Boiler Enable
0
1=ON / 0=OFF
0
1
1
00005
Tank Thermostat
0
1=ON / 0=OFF
0
1
1
Discrete Inputs
10001
Manual Reset High Limit
0
1=ON / 0=OFF
0
1
1
10002
Flow Switch
0
1=ON / 0=OFF
0
1
1
10003
Gas Pressure Switch
0
1=ON / 0=OFF
0
1
1
10004
Louver Proving Switch
0
1=ON / 0=OFF
0
1
1
10005
Blower Proving Switch 1
0
1=ON / 0=OFF
0
1
1
10006
Blocked Drain Switch
0
1=ON / 0=OFF
0
1
1
10008
Flame 1
0
1=ON / 0=OFF
0
1
1
10009
Enable
0
1=ON / 0=OFF
0
1
1
10010
Tank Thermostat
0
1=ON / 0=OFF
0
1
1
10011
Blocked Flue
0
1=ON / 0=OFF
0
1
1
10013
Blower Proving Switch 2
0
1=ON / 0=OFF
0
1
1
10021
Flue Damper Proving Switch
0
1=ON / 0=OFF
0
1
1
10023
Flame 2
0
1=ON / 0=OFF
0
1
1
10033
Run-time Contacts
0
1=ON / 0=OFF
0
1
1
10034
Alarm Contacts
0
1=ON / 0=OFF
0
1
1
10035
SH Pump
0
1=ON / 0=OFF
0
1
1
10036
DHW Pump
0
1=ON / 0=OFF
0
1
1
10038
Gas Valve 1
0
1=ON / 0=OFF
0
1
1
10039
System Pump
0
1=ON / 0=OFF
0
1
1
10044
Vent Damper Relay
0
1=ON / 0=OFF
0
1
1
10046
Gas Valve 2
0
1=ON / 0=OFF
0
1
1
10049
Blower #1 Power
0
1=ON / 0=OFF
0
1
1
10050
Blower #2 Power
0
1=ON / 0=OFF
0
1
1
10051
Spark Igniter
0
1=ON / 0=OFF
0
1
1
3
Memory Map
ModBus Instructions