Issue
TC300 Series Networking Digital Fan Coil Thermostat - Modbus Protocol Documentation
Product Line
Field Devices
Environment
TC300 Series Digital Fan Coil Thermostats
Cause
Modbus protocol information is needed in order to perform Modbus integration to the TC300 Series Digital Fan Coil Thermostats.
Resolution
The TC303 thermostats come with the option of Modbus communication for both 2- and 4-pipe configurations. Modbus is an open, widespread and well established serial communication protocol used within building automation. The support of Modbus communication allows simple integration of the TC303 thermostats to a building management system, using standard Modbus serial communications. The following models provide support for Modbus connectivity:
- TC303-3A2LM
- TC303-3A4LM
- TC303-3A2DLMS
- TC303-3A4DLMS
- TC303-3A2DPMS
- TC303-3A4DPMS
The TC303 thermostats communicate as a Modbus RTU slave device over a serial RS-485 connection, allowing for the transfer of real time data. Thermostats manufactured from November 2018 (2018-W44-4)* onward can be configured to communicate at 9600 (default) or 4800 bps. The communication parameters for TC-300 thermostats manufactured prior to this date cannot be adjusted and are fixed as follows:
- 4800bps Baud Rate
- 8 Data Bits
- Odd Parity
- 1 Stop Bit
The actual Modbus address of the thermostat can be set for each individual device on the RS-485 network. The address is defined via the parameter menu on the thermostat itself. The address range available is from 01 to 32 and is defined under menu item 04 of the parameter settings.
For full details on this, other parameter setting options available and Modbus communications parameters/registers, please refer to the Installation Instructions.
Connection to the RS-485 network is made via dedicated terminals on the back of the thermostat and marked A (+) and B (-).
TC300 Series Digital Fan Coil Thermostat Installation Instructions
TC300 Series Modulating Fan Coil Thermostat Installation Instructions
* Note - The Installation Instructions have not been updated to include the information that thermostats manufactured from November 2018 (2018-W44-4) onward can be configured to communicate at 9600 (default) or 4800 bps.
