Power relay
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Are you sure that relay board has isolation? I don't see an optical isolator on it.
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Okay maybe not that one but there are units for a few £'s more which do.
Regardless - how would you advise connecting it?
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How about this one?
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That one has a 4-pin device on it that is probably an opto isolator.
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It's a bit of a different level of investment if you don't have a system up and running, but I have the printer on a z-wave plug which also monitors power consumption (bit of an eye opener) simplifies setup a fair bit.
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Sure thats one way of doing it and I think asking David to consider some sort of interface to radio switched plugs/alexa etc. could be a great addition. But I'm just considering simple M80 for on and M81 for off setup. I have 3 machines running duet board now so a simple solution is what I'm after. I have a power monitor running to the bench for all my printers it is interesting I agree.
If powering the duet from external 5v should we use the 5v & GND pins in the PS_ON header? Or can plugging in a usb charger/adaptor to the usb port suffice long term?
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You can feed power via the USB port or the external 5V connector (the one with the PS_ON pin), it makes no difference.
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Thank you.
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Share the results and diagrams if works. I'm thinking on use a similirar relay board with ps_on pins of the duet to fire the camera button and makes timelapses
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I'm still none the wiser as to how best to connect it. It seems some of these relay modules can accept a high or low signal, so set to low, I would expect you can ground the IN pin on the relay to the PS_ON pin on the duet to trigger it. For those relay modules which only accept a high signal then if PS_ON goes to ground when M80 is sent, I think it might be best to use something like a logic inverter to reverse the signal. https://www.ebay.co.uk/itm/LOGIC-SINGLE-INVERTER-GATE-5SC70-Part-SN74LVC1GU04DCKT/351615798176?epid=1339373369&hash=item51ddef4ba0:g:QM8AAOxy8HlSa77O
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If you choose a relay module with an optically isolated input, then it will hopefully have + and - control input terminals separate from the power supply terminals. In which case you can connect the input terminals to +3.3V or +3V and PS_ON.
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To use it as a camera trigger, I need to execute m80 and followed by m81. What interval would I have if I put them one below the other in the gcode?
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More than a microsecond, but possibly less than a millisecond.
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I can't tell if that is a joke or not. I will read about gcode waits and try to trigger the camera without the duet first
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Okay so I've settled on this one:
So to make this work, I would hook up +5v from the duet to both VCC and CH1 pins, then GND to PS_ON? -
No. Please post a photo of the back of the board with better lighting and focus, so that I can see the PCB traces clearly.
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The traces still are not very clear. But I think that CH1 and GND are the input signal, connected to the input of the opto coupler through a series resistor, while VCC and RGND provide power to the relay. If that's the case, connect VCC to +5V and RGND to ground. Connect GND to the Duet PS_ON output, and connect CH1 to either +5V or +3.3V.
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Okay thanks David. I'll have a play with it on the bench before connecting it to a duet board.
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Okay so it did end up working as I had suggested originally, I spoke to the vendor who said to ignore RGND and use VCC, GND, CH1 pins. In fact it did not seem to matter whether PS_ON is connected to GND or RGND so I presume they are tied. So connecting VCC and CH1 tied to +5v on expansion connector and then GND to PS_ON switches the relay on M80, and off on M81.
Nice bright LED too if you are going to put it under a cover of some sort it will shine through. Mine is going to live under the PSU end cover which keeps small fingers off the 240v wiring.
