Issue
Is there any way to connect two smart sensors (TTS-SD-LCD-1) to one VAV controller (b3855-V) or other BACnet control board?
This is a simple office application but the spec requires Smart sensors for VAV boxes and a few large zones have two sensors controlling one box.
Environment
CX bCX
b3
smart sensor, TTS-SD-LCD
Cause
Is there any way to connect two smart sensors (TTS-SD-LCD-1) to one VAV controller (b3855-V) or other BACnet control board?
Resolution
More than one smart sensor connected to a Continuum VAV box will present some issues.
The smart sensor uses a three wire connection to the controller smart sensor port as follows:
The controller communicates with the keypad and the display of the Smart Sensor device over a single wire (the PWR connection).
The RET line is the return for both the communications line and the internal thermistor.
The input signal is the active lead from the Smart Sensor thermistor. Its connection is labeled according to a controller-specific input assignment. This input must be configured as a general Temperature input.
The controllers are not designed for more than sensor - having only the one smart sensor connection. You'll only
have one temperature input and the reading will be incorrect if you wire two thermistors to the one input.
If you are just trying to display the same info and/or provide a second location for override, that may work. You'd need to test it - and it would not be a supported configuration.
