An OEM of plant growth chambers was looking to simplify their chamber designs. Their goal was to reduce manufacturing costs and improve product reliability and usability.
Most chambers have different settings to simulate day and night conditions. These can include temperature set points, RH set points and lighting control. The OEM was using an analog controller with two set points. A mechanical timer selects which set point is connected to the controller and the indicator shows the actual chamber temperature. Two separate bulb and cap thermostats are also utilizes for high and low alarms.
To simplify the system design, Watlow® specified a custom design by combining many features into one controller. The controller had two RTD inputs, two digital inputs and five outputs made it ideal for this application. The unique design of the custom firmware enables the OEM to stock a single controller able to handle three different chamber configurations. One RTD input senses the main cabinet and the second one was for the alarm, replacing the two bulb and cap thermostats. The custom firmware allowed a user to enter day and night set points, replacing the analog controller. The five digit LED display replaced the digital indicator. The new custom solution also contained a real time clock and battery to maintain the time of day in the event of a power outage.