Tool Enable - M15 - IOT Relay - & Breakout board (auto turn off/on router)

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

Hey Bob,

@crz383

@Aiph5u

The router and the dust collectors should be both switched on with M3/M4 commands so the ‘tool-enable’ pin is the correct output.

I guess I wasn’t clear. I wondered whether I could control the router and the dust collector independently from Gcode. Some posts imply that it’s desirable to have a delay between powering on the router and powering on the dust collector (or vice-versa). I found “vacuum switches” that provide such a delay, but their delay time is fixed. I thought that, if I have to use 2 relay boards anyway and if there’s a way to control them independently from Gcode (rather than in parallel from pin 15), I could implement whatever delays I wanted in Gcode. (I realize that the two relay boards might have to be different, because of the different electrical characteristics of the outputs, such as pin 15 and L1.).

If you want the dust extraction to be triggered relatively from when the router is switched on by M3 command → ‘tool-enable’ (pin 15), you can do this with electronics that implement a delay. I do not know what is there on the market for consumers, as I am a person who usually is building my own things with electronic components, and in this case you are able to select the delay you like. I know today some people use an Arduino for this but I would say a NE555 is totally sufficient for this.

Just a note in case you might want to divert M7/M8 commands (workpiece coolant control) from their intended use in order to use L1/L2 outputs for turning on dust extraction, you got to make sure that these commands are inserted into your toolpath. Whether you achieve this by selecting ‘workpiece coolant on/off’ in your CAD/CAM software, or by manually editing your g-code toolpath, or by hacking the post processor, is the choice then.

@crz383

@Aiph5u

Also you don’t forcibly need “IoT” relays, if you can wire things you can simply buy a relay on a small board with screw terminals.

I realized that I could use a relay board rather than an IoT relay; the IoT relay seemed like it might be simpler, if a bit of overkill.

The question is, are you a consumer, or are you an electrician/electrical engineer (or a consumer that is able to acquire some of an electrician’s knowledge and capabilities). In the first case you are forced to buy things you can simply plug together, in the second case you can wire together some components you’ve chosen. In both cases you have to read the specifications and the manuals of what you buy or intend to use carefully.

@crz383

@Aiph5u

On the controlling side of relay, you got to know that generally you do not drive the relay with the power from the I/O pin sink/source current of AVR microcontroller (datasheet ) pins directly which would be max. 25 mA. In order to drive relays, usually you have a power supply for this, e.g. one with 24 V which is a common voltage for this.

Is this just pointing out that I couldn’t connect pin 15 directly to a bare relay, as distinct from a small board containing a relay, as shown in earlier posts in this thread (such as one from charleyntexas).

Yes, and the need to power the relay board with a power supply as shown above in this thread (whilst the ‘IoT’ type of relays on the first post get their power internally so you don’t have to worry about this)

I don’t know which relay charleyntexas referred to as he refers to a lot of things over time (you omit the link to the posting you mean), but you can only connect something directly to the pins of the AVR microcontroller if you are sure it never sucks more than 25 mA. Usually this condition is fulfilled if your relay is powered by a separate power supply and has a driver transistor in front of its relay coil. The pins of the AVR are used as triggers for drivers, not as relay drivers themselves. Using a dedicated power supply for driving relays (e.g. a DIN rail-mounted specimen as shown above in this thread) takes this into account as it provides power sufficient for driving a relay (and perhaps also for more than one). For example a bare Omron G4A relay wants 75 mA @ 12 V DC and 37.5 mA @ 24 V DC. Also when you run a CNC machine you easily have more than one relay that you might want to use.

Also if you use these relays available with some circuitry around them on small boards that I mentioned earlier, as I already said, they have optocouplers on it which means the relay-triggering circuit is galvanically isolated from what they switch, which is safe.

PS: Note: You might be interested in this:

• Satoer’s Onefinity Remote Control Panel