Power relay
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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.
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Why dont connect the 5v/CH1 to the 5v on ps_on header?
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Because and it took me a few minutes to work this out yesterday, its a 5v input pin, not 5v output! There is a diode on it.
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Ok ok. Then 5v/CH1 go in any 5v output and gnd to ps_on.
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By any I presume it will have to be either the 5v output from your 5v power source for the duet board, or from the board itself with the ext-5v jumper attached. Otherwise the relay wouldn't have a ground.
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So soldered a link across CH1 and VCC, so I only need two wires. Works great. One thing I did notice, when I send an M81, the console reports a Warning: VIN under-voltage event (X.Xv) .
Not really a problem, but maybe the under voltage monitor routine should be shutdown on an M81 since obviously, the voltage is going to drop if you disconnect the PSU. The restarted on an M80? Perhaps it serves as a useful marker in the log to show when it shut off maybe?
So now using in start gcode
M80 ; PSU ONThen in end gcode
M109 S50 ; lower hotend temp to below glass transition temp
M116 ; wait for temps to stabilise (so PSU does not shut off whilst hotend is hot)
M140 S0 ; turn off bed temperature
M84 ; disable motors
M81 ; PSU offThis allows the hotend to get down below glass transition for any filament.
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M81 events are logged anyway. The reason I don't suppress the under voltage message is that in some situations the firmware executes M81 without knowing whether it will have any effect. But I guess it could ignore under voltage events for just a few seconds after M81.
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Thanks David. Was just a thought, might be worth trying the idea of ignoring it for a few seconds, if you have time to do so - it just seems more logical not to report an error on an intentional disconnection of Vin power.
So I have wired up two of my Duet enabled printers with these relays, both working fine.
Found something like this lying around too:
Which means you don't need any more mains sockets for each printer. It provides 2 usb ports, one to the duet usb port to provide 5v power, and a spare one for an ip camera or something else, whilst also having a passthrough port for the printers PSU mains supply.
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Just a quick question. On one machine that I have added a power relay to, I connected the EXT 5v jumper (removing the INT 5v one). On another machine I just realised I have not removed the INT 5V jumper yet they both behave exactly the same. I am powering them via USB charger, via the USB port.
Is there something I'm missing? Is the functionality of this jumper related to powering via the 5v input pin on the PS_ON header block? Am I potentially doing any damage having the jumper set wrong? I presume not as I've about 4 hours printing on the machine set to INT 5v without any issue?
Just for information a USB charger rated at 1amp (but probably less as it was generic and not great quality) does not provide enough current to reliably power the board via the usb port.
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That's an interesting solution. I use a significantly more heavyweight approach. I am using a 5V power pins from a 5V PSU and the PS_ON pin goes to the raspberry pi – then I have a webapp which monitors GPIO pins and when it gets the right signal it toggles the connected relays on a 4 relay board -- 2 for mains going to the 24v PSU and 2 for mains going to the heated bed -- I've yet to find an SSR which doesn't leak AC, so I like to cut it's power when the machine is not on. I also am doing a double throw to break both live and neutral on both 24v PSU mains and bed mains -- belt and suspenders
The pi is there for webcam streaming and other things which I am used to having OctoPrint do for me.
