I'm a programmer of many years, but I am new to the electronics world. As a project I want to control some heating and pumps from an Arduino by reading DS18S20 thermometers. I've written a C# program to perform the main processing logic and pass requests to the Arduino to do the switching, which the interface works great so far.
I received a 8 Relay Module http://www.aliexpress.com/fm-store/312788/210933836-481242970/free-shipping-8-Channel-5V-Relay-Module-for-Arduino-PIC-ARM-AVR-DSP-wholesale-price.html (not purchased from here, but is has the main info on it) to allow me to switch the loads of the pumps and heating.
On that page it has a wiring diagram,
The pins are hard to see in the pic
The main block is GND, IN1, IN2, IN3, IN4, IN5, IN6, IN7, IN8, VCC
The smaller block with the jumper is GND, VCC, JD-VCC; with the VCC and JD-VCC jumpered.
Now I assume the jumpers allows the relay module to take power from the VCC of the main pin block.
To test wire it up I ran
ARDUINO +5v to VCC on the main block
ARDUINO Earth to GND on the outer smaller block
Digital PIN 9 to a IN1 (also tried other IN pins)
I set the ARDUINO to
Now when the digital out is HIGH, the relay is OFF
When it is LOW, the relay is ON
I though it would have been the opposite?
Also as a side question; when want to run it properly with more than one relay I'm going to feed power from an external +5v power supply. How should I wire it then?
Thanks in advance
edit: I should add when I jumper a LED across the pin and earth it behaves as expected.