I'm a complete newcomer to component level electronics, so bear with me. I'm building a fully scalable environmental control and irrigation system for hydroponic gardens that can be as small as a personal garden and as extensive as a multimillion-dollar industrial setup. Yes, I know this project is currently way over my head, but I have broken it down into phases and plan on taking my time learning bit by bit to bring this into reality as I learn.
I'm currently in Phase 1, which I have defined as making one self-watering plant pot. Simple enough, I have a circuit built that is currently just sending a signal to an LED when the pump would be running. The software and sensor are working properly and I am getting the LED to light for 1-second pulses every 5 seconds while the sensor is reporting low moisture and it stops when it hits the upper limit, cool. Now I need to hook up the relay module.
Knowing I was going to scale this up into a system that controls groups of plants I wanted to use a 16 channel relay module right from the beginning to make less work for me going forward. The relay I purchased (listed below) may have been a poor selection as the device to use. I can't figure out how to get it to trigger the relay.
I have the relay module powered through a wall wart 12v power supply. On the business end of the relay, I have a 9v battery and a 12v pump. The battery drives the pump just fine for testing purposes, and I don't have another power supply to use yet, yay Christmas strain on the mail system! So I am fairly confident everything in front of and behind the relay module is working just fine.
I have the signal wire coming from the Mega pin 12 into the breadboard with the indicator LED and another lead. The lead goes to the channel marked X1 on the module and the motor is connected to the K1 relay. When the LED illuminates I am getting no response from the pump.
I have a second 16ch relay module in the mail as well that has a better interface and is intended for use with Arduino, but if I can make this one work it will be a lot less expensive for the larger scaled end of the project. I saw in the listing for the module I am using it is a 5/12/24v 5mA board, but I don't see anything to select different voltages and the board came with absolutely nothing for documentation. One of the ports on this relay is labeled XM right next to DC+ and DC- on the input terminal. The rest are numbered X1 through X16. What is this XM used for?
My only theory is that the board's signal wire isn't supplying enough amperage to the relay module to trigger it, but I have no idea if that's even on the right track. I ordered a multimeter, which is also in the mail.