MODBUS COMMUNICATIONS HeatNet Control V3
Page 118
MODBUS Communications
The FlexCore CK -Series control can be controlled using Modbus commands to Enable/Disable the boiler/system. A connection
to the Console Modbus Port on the Communications board is required. The Master Boiler assumes the role of MEMBER, RTU,
192Kb, 8 bits, Even Parity, 1 stop bit, when connected to a BMS (Building Management System).
The Member Boilers should not be connected to a BMS system other than to view Read Only addresses. Refer to
http://www.rbiwaterheaters.com/ website for greater detail on communicating with Modbus, BACnet, or LonWorks protocols.
Boiler01 = The Modbus connected boiler (Master or Standalone)
Boiler02 = Member 2
Boiler03 = Member 3
…
Boiler16 = Member 16
*All Setpoint temperatures must be set in Fahrenheit
MODBUS Input/Output Variables (Read/Write)
Heat Demand/Request. Setting the state
member of this variable will put the boiler
in heating mode.
0 = no heat demand
1 = heat demand
System Setpoint Timer
The system setpoint timer and system
setpoint work in tandem to externally
control (i.e. a BMS - building management
system) the operating setpoint. The
setpoint (countdown) timer should be
loaded with a timeout value (in seconds)
prior to writing the system setpoint. When
the timer reaches zero, the control assumes
that the BMS is no longer operating and the
local setpoint (saved on the control) is
reloaded. This is a failsafe feature used to
help safeguard the system in case of BMS
failure. If the setpoint timer is not written,
a default timeout value of 60 seconds is
assumed.
System Setpoint (see SetpointTimer)
Enables/Disables outdoor air reset mode.
Outdoor air reset setpoint. Temperature at
which boiler shuts down.
Boiler water temperature setpoint when
outdoor air temperature is at the high
outdoor air temperature setpoint
(OARHiAirTemp).
High outdoor air temperature setpoint.
Header/Supply temperature setpoint when
outdoor air temperature is at the low
outdoor air temperature setpoint
(OARLoAirTemp).
Low outdoor air temperature setpoint.