7
Modbus Instructions
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
SYNC Boiler Memory Map
Coils
Address
Description
Default
Unit
Min.
Max.
Resolution
00001
Boiler Enable / Room Thermostat 1 / Stage 1
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 1
0
1=ON / 0=OFF
0
1
1
10002
Flow Switch 1
0
1=ON / 0=OFF
0
1
1
10003
Gas Pressure Switch 1
0
1=ON / 0=OFF
0
1
1
10004
Louver Proving Switch 1
0
1=ON / 0=OFF
0
1
1
10005
Air Pressure Switch / Flap Valve 1
0
1=ON / 0=OFF
0
1
1
10006
Blocked Drain Switch 1
0
1=ON / 0=OFF
0
1
1
10007
Auto Reset High Limit 1
0
1=ON / 0=OFF
0
1
1
10008
Flame 1
0
1=ON / 0=OFF
0
1
1
10009
Enable / Room Thermostat 1 / Stage 1
0
1=ON / 0=OFF
0
1
1
10010
Tank Thermostat
0
1=ON / 0=OFF
0
1
1
10017
Manual Reset High Limit 2
0
1=ON / 0=OFF
0
1
1
10018
Flow Switch 2
0
1=ON / 0=OFF
0
1
1
10019
Gas Pressure Switch 2
0
1=ON / 0=OFF
0
1
1
10020
Louver Proving Switch 2
0
1=ON / 0=OFF
0
1
1
10021
Air Pressure Switch / Flap Valve 2
0
1=ON / 0=OFF
0
1
1
10022
Blocked Drain Switch 2
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 1
0
1=ON / 0=OFF
0
1
1
10035
CH Pump 1
0
1=ON / 0=OFF
0
1
1
10036
DHW Pump 1
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
10041
Run-time Contacts 2
0
1=ON / 0=OFF
0
1
1
10042
Alarm Contacts 2
0
1=ON / 0=OFF
0
1
1
10043
CH Pump 2
0
1=ON / 0=OFF
0
1
1
10046
Gas Valve 2
0
1=ON / 0=OFF
0
1
1
3
Memory Map
