Xiomara 1502 control unit

The first component to take for an elaborate test is the Xiomara 1502 control unit.

The control panel can be used to control the following parameters:

  • Time – How many minutes and seconds the IR lamp stays on
  • Temperature  – I have to find out, but based on the thermometer attached to the unit, I think the control unit switches the IR lamp on and off based on the temperature setting and the measured temperature.
  • Fan & overhead light – Simple on & off switch

After plugging the control unit into a power outlet a display test is performed and after a couple of seconds the unit can be controlled. After setting the time and temperature, the session is started by pressing the start/stop button for 2 seconds. This wil activate the IR lamp and optionally the fan & overhead light, based on its setting. The control panel shows the time left until the sessions ends. The end of the session is indicated by a loud beep from the control unit.

Pressing the start/stop button during the session for 2 seconds will stop the session and reset the timer. Pressing the start/stop button for 6 seconds will put the control panel in stand-by mode.

To give a general idea of how the unit works I will connect a fan and a regular light to the control unit in a video showing walking through the steps of a regular user session.

I will also hook up an oscilloscope to the power output of the control unit that is used to power the IR lamp to check if the IR lamp is simply switched on and off or that the IR lamp is variably controlled.

I will test the control panel to answer the following questions:

  1. Which parameters are controlled by external pins 5 and 7 (with pin 6 presumably being a ground or positive wire)?
  2. Can the unit be controlled remotely / externally so that the parameters can be changed through another interface (e.g. an app)?
  3. Does the unit simply switch of the power to the IR lamp when the desired temperature setting has been reached or does it use a (smooth) PID like algorithm?

During testing an instance incurred in which the power to the IR lamp always remained on, independent of the status light of the IR lamp on the control panel. After a reset of the device the problem disappeared. I have not been able to recreate this situation.

After testing I found out the following:

  • If you want to put the control unit into stand-by mode, the unit always initiates a session for 1 second before it switches to stand-by. Both the IR lamp and fan & overhead light will switch on during this procedure.
  • While in a session, only the time remaining is visible. The current temperature is only visible when there is no session active.
  • According to the manual, the down arrow can also be used to mute the beeper. It doesn’t mention how.
  • The IR lamp is actived if the current temperature is at least 3 degrees Celsius lower the the configured temperature.