Lochinvar 1.5 - Manual (Page 15)

15
5
Unit Operation
(continued)
Demand Confi guration: ENABLE = INACTIVE; BMS = ACTIVE
In this confi guration the unit is controlled by setting the modulation setpoint from 0 - 100%, or the setpoint. The setpoint
command will be determined by the parameters in the control.
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 Defi nition Bit Value (HEX) Action
40001 Confi guration 00 04 Set Confi guration to read 40003
40003 Rate Command 00 00 Sets Modulation % or Setpoint
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 confi guration 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 Crest 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 Confi guration: ENABLE = ACTIVE; BMS = ACTIVE
In this confi guration the unit is controlled by providing an enable signal. The setpoint command will be determined by the
parameters in the control 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 enable and 0-10V
BMS signal. These signals will be sent to the unit via ModBus.
The holding registers will need to be set as follows:
Holding Registers Defi nition Bit Value (HEX) Action
40001 Confi guration 00 05 Set Confi guration 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 confi guration 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