Lochinvar SYNC Modbus Communication 1.0- 1.3- 1.5 - Manual (Page 15)

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5
Unit Operation
(continued)
Demand Configuration 6
In this configuration the unit is controlled by setting the modulation setpoint from 0 - 100%.
Rate command will be 0 - 100% of the modulation range.
All sensors and limiting devices should be hardwired to the terminal strip on the back of the unit excluding the 0 - 10Vdc signal.
This signal will be sent to the unit via Modbus.
The holding registers will need to be set as follows:
Holding Registers Definition Bit Value (HEX) Action
40001 Configuration 00 04 Set Configuration to read 40003
40003 Rate Command 00 00 Sets Modulation %
For proper hexadecimal conversion of rate percentage, please refer to the Rate and Temperature Conversion section on page 17
of this manual.
NOTE: To ensure proper operation re-send the configuration bits to holding register 40001 prior to issuing a command.
Hot Water Generation
Hot water generation can be accomplished with one of two methods when a SYNC boiler is connected to a BAS system, DHW
with direct control, and DHW with remote control.
DHW with direct control:
This is the typical installation with a hot water generator in close proximity to the boiler with the tank thermostat, or tank
temperature sensor, wired to the terminal strip of the unit.
Demand Configuration 5
In this configuration the unit is controlled by providing an enable signal and a rate command through Modbus communications.
The rate command will be 0 - 100% of modulation.
All sensors and limiting devices should be hardwired to the terminal strip on the back of the unit excluding the thermostat enable
and tank thermostat enable signal. These signals will be sent to the unit via Modbus.
The holding registers will need to be set as follows:
Holding Registers Definition Bit Value (HEX) Action
40001 Configuration 00 05 Set Configuration to read 40002 & 3
40002 Coils 00 01 Enables unit (00 00 disables unit)
40003 Rate Command 00 ## Sets Modulation % or Setpoint
NOTE: To ensure proper operation re-send the configuration bits to holding register 40001 prior to issuing a command.
For proper hexadecimal conversion of rate percentage, please refer to the Rate and Temperature Conversion section on page 17
of this manual.
Modbus Instructions