How to Connect a Solar Light Sensor to an Analog Input Module | Link4 Controls

How to Connect a Solar Light Sensor to an Analog Input Module | Link4 Controls

The Solar Light Sensor needs voltage (+12VDC) to power it and it outputs a current which is passed through a resistor (3.8K R6) for the controller to measure the voltage that corresponds to the light level. 

There are 3 ways to do this, listed below from easiest to hardest:

  1. Use a Weather Station Input Module and use input 3.  This input has been pre-wired to send 12VDC to the light sensor (JP19), and to receive the current back and pass it (JP10) through a 3.83K resistor (R6).  Nothing else needs to be done.

  1. If you don’t have a WS input module and have a regular input module instead, then you need to supply an external 12VDC source to the sensor. 
    1. Note that the ground of the supply must be tied to the negative input of the input module.  This is tied to the signal ground (JP10).
    2. Be careful that the negative side of the light sensor is tied to the + input pin, which sends the current (JP9) to the sensing resistor (R6).  This is unlike the WS wiring, where the negative side of the sensor is tied to the – input pin instead.
    3. Be careful of possible noise in this setup.  The 12VDC ground could have many things on it, which could inject noise into the system.
    4. You can use any spare analog inputs for this.  Just make sure the sensor map matches up accordingly.

  1. If you have a sharp blade and a soldering iron, you could modify JP9 and JP10 so the analog input module could be converted to a WS module.
    1. This is not recommended for most people.
    2. This will void your warranty.
    3. Must keep track of this change and ensure that once the board has been changed, ONLY the solar light sensor is connected to this modified input.
    4. Take the cover off and modify JP9 to send the internal 12VDC out.  Cut left side and solder right side.
    5. Modify JP10 to send the current to R6 instead of ground.  Cut right and solder left.

Summary

You can connect the Solar Light Sensor to a regular analog input module using an external 12VDC supply and proper wiring. While it’s not as plug-and-play as the Weather Station Input Module, it still provides accurate light readings when installed correctly.

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