Software Algorithm

This software provides simple thermostat functions. The inputs and outputs of the thermostat can be configured as needed using the Cristal Controls "BACnet Browser" software application. Up to 2 cooling stages dry-contacts type can be configured and up to 5 heating stages (2 stages dry-contacts type, 2 modulating outputs and an emergency heating stage).

With the BACnet objects, it is possible to: apply occupied or unoccupied mode, do some shedding by adjusting maximum power for the thermostat and select heating or cooling mode only.

All outputs can be controlled directly, but depending on the thermostat configuration, they can also be controlled from the thermostat application.

Temperature

After being powered ON, it takes at least 15 minutes before temperature become stable and accurate. This delay must elapse before the electronic components warm the enclosure and stabilize readings.

Also, an internal filtering algorithm is applied on temperature readings to avoid fast glitches on readings. For large permanent changes, this has the effect of seeing 95% of the change in 3 minutes.

The thermostat algorithm continues even if the temperature is out of range. If the temperature is below 10° Celsius, the thermostat uses a temperature value of -99° Celsius for his internal calculation. If the temperature is over 60° Celsius, the thermostat uses a temperature value of 99° Celsius for his internal calculation.

Thermostat configuration

The thermostat configuration is done using the "Config.bin" file available in the BACnet network. The file is used to configure the 2 cooling stages, the 5 heating stages and to choose the used outputs for the activated stages. The temperature sensor can be configured to use the internal sensor or add an external sensor connected to the corresponding input. Unused relays and inputs can be configured to accomplish some specific tasks.