Depending on the usage scenario, limitations or flexibilities in the Modbus TCP slave, the data mapping will vary. Therefore, the following mapping is only the prefered mapping by NODA. As such, it can be changed in agreement with NODA to match the specific situation.

Modbus mapping for a typical building

Word Order: Big Endian
Byte Order: Little Endian

OrderValue nameEncodingAmplificationUnitDirectionFunction Code
2Outdoortemp Offsetuint161/100KelvinWrite6
3Primary Flow (Supply) Temperatureint161/100CelciusRead3
4Primary Return Temperatureint161/100CelciusRead3
5Primary Flow Volumeint161/10*l/h*Read3
6Primary Side Volumeint161/10*m3*Read3
7Primary Heat Energyint161/10*MWh*Read3
8Primary Heat Powerint161/10*kW*Read3
9Secondary Side (#1) Flowint161/100CelciusRead3
10Secondary Side (#1) Returnint161/100CelciusRead3
11Secondary Side (#2) Flowint161/100CelciusRead3
12Secondary Side (#2) Returnint161/100CelciusRead3
XXSecondary Side (#n) Flowint161/100CelciusRead3
XXSecondary Side (#n) Returnint161/100CelciusRead3

* Depends on specific circumstances

The structure outlined in the table can repeat if the Modbus TCP slave interfaces with several regulators and or control points.

NOTE: If additional secondary side circuits exist, they should be included.

NOTE: Holding register numbers are intentionally not outlined as they likely will vary from one Modbus TCP slave to another.