Was wondering if anyone has managed to use the " https://flows.nodered.org/node/node-red-contrib-i2c " to trigger the relays on a board like this one [image] MakerFocus Raspberry Pi Expansion Board 4 Channel Relay Board Module Power... I used the scan node and it d…

@socialdeviat I just figured it out ! You're in luck. Its fairly simple tbh, Here is my flow [{"id":"c6535213.beea8","type":"switch","z":"686e77f4.058018","name":"Relay Triggered ON","property":"payload","propertyType":"msg","rules":[{"t":"eq","v":"AN1C1 ON","vt":"str"},{"t":"eq","v":"AN1C2 ON","…

Is there some more info available for the board? Datasheet with protocol description maybe or example code in other prog language.

I have a flow that uses a PCF8574 IO expansion module to drive a bank of 8 relays. It should give you an idea of how to do it. You don't have to use the PCF8574 IO board, just drive the relays via GPIO pin on the device of course. [{"id":"6ad99e0f.f50c98","type":"tab","label":"Relay Control (PCF8…

Looking at the Wiki for this board, it is a direct read and write i2c device, just like the PCF8574 is. The control method is almost identical. You just need to pass (write) to the right address, the correct number of bytes, the right byte values, in the right order to drive the relay state(s).

I am in the same boat, just registered to follow this particular discussion. Have the same board, I can manually trigger the relays via i2set commands on the rpi console, but cannot seem to figure out the way to make Node-Red trigger with a button/timer and setup the flows. command on RPI cmd line…

Ok, lets take this one step at a time. My flow does 3 things. It determines if I have a PCF8574 board present on the i2c bus. If so, it sets a flow variable to true. Other flows use this to determine if they can do their respective task(s). The register flow captures the state of the PCF8574…

Gotcha, that gives me some good aides in understanding the flow I'm looking at. I'll dive in a bit and tinker some more. Appreciate the break-down and time you've given!

Sure.... since could not find a working PCF8574 node for NR, I created what I shared. The more people that learn from it, the better, I say. If you have more questions just asked. I or others I am sure will help as needed. We will not give answers by default but will given examples that you can …

Agreed... to be fair, I didn't catch that this was an I2C relay board, I had flows already pre-configured to manage a RPI GPIO controlled node-red setup. (I can still do this, but hey... learn something new!) I am officially in ~8hrs into the world of I2C.

I have older relay boards that are direct GPIO driven. The concept is similar that you may want to retain the 'state' of the relays, so you always know which is on and off. Direct driven is easier since no i2c interface, but you use a lot of GPIO pins of course. Once I got the i2c interface worki…

This flow is fantastic. Thanks for the insight, I did not know about the PCF8574 IO expansion module. This would be super helpful for me in the case of expansion !

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Triggering i2c relays via node red

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juntiedt 9 October 2020 11:07 14

this is an seed i2c 4 relay board solution

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Triggering i2c relays via node red

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