[Al_The_Man]

The AC output version?
While the SSR is on, what happens if you short the two output terminals?
Al.

[greenjeens]

If i click it on real quick in mach 3 then quickly short the outputs it will work and ignite. However if i click it on it mach 3 and do not short the pins it will not ignite and the cutmaster 52 plasma cutter gives me an error.

[greenjeens]

Even though it works as in activating the torch with no ignition, is it still the relay that's the problem, having to short the 2 output pins to make it work?

[SteveWill]

I hope Al the man posts again as he seem to know about these things. I know electronics but have no idea of the rest of your system. What i would try next is to drive the auto relay with the SS relay. Leave the SSR connected to Mach 3. I would move the output wire to the auto relay output. Connect 12vdc to one side of the control/coil side of the auto relay. the other side to the auto relay to one SSR output the other side of the SSR to ground. See if it now works. The fact that the gas is flowing tell me the relays are working but the characteristics of the SSR output maybe such that the fire circuit is not working, the Auto relay output is more like a mechanical switch. The reason I am using the SSR is because I do not know if the Mach3 driver has enough current drive to power the Auto relay.

[Al_The_Man]

I would give up on the SSR, Especially if you are using the AC output version, it most likely is going to be incompatible with the torch input, AFAWK a DC version may not work.
At least with a relay you can be sure it is the same as when you just use a switch.
If you want to use your auto relay, then use a source of 12vdc from the PC itself or wherever, then if you have access to a pin on the P.P., use the circuit I mentioned earlier using a 2n7000, I always keep a couple dozen of these on hand as they are very usfull when operating different voltage relays from low current 5vdc, otherwise, if you have the Gecko you should be able to use the relay just like they show in the manual.
Al.

[pimpbike]

I have spent countless hours trying to get an SSR to work properly with the G540. It worked sometimes and then would cause weird problems. Sometimes it would freeze the PC among other glitches. I tried changing out the PC trying another brand SSR then I gave up and went to a regular 24v coil relay and all my problems went away.

[holobox]

Many(most) solid state relays contain an SCR or thyristor to switch the load - these are ONLY good for switching an AC source voltage into a load. (think AC outlet and light bulb here!) I wouldn't even attempt to make this work for this purpose. While some SSRs use MOSFETs and can switch a DC load I'd avoid those also. What you really need is a honest-to-goodness switch closure here - and a mechanical relay is the only way to get that reliably!

If you are fortunate enough to have the detailed schematic for your cutter - I could recommend an optoisolated circuit that would work if you really want to go the solid state route. As for me - I have a friend's Harbor Freight 95136 and those details are completely missing from the manual, web, etc.

In general, forget the SSR!

Charlie

[pimpbike]

I was trying to use an SSR to turn on a Router. The G540 did not like it.

[holobox]

Here's my recommendation using opto-isolator, mechanical relay, etc. If you mind your polarities you'll only need the lower opto channel. (actually the 390ohm resistor in the BOB is good for the single channel, if you use both channels cut that value in half!) What you see here is active (torch on) with a high logic level on the ~spindle control pin from the BOB, that assumes a switch closure does the trick! Probably good idea to procure a relay with normally open and normally closed contacts. You really don't want to be powering that relay when you aren't cutting. About anything will work with the snubber diode shown at the arrow. (1N914, !N4004, etc.)

If you can't find a +12Vdc supply in your plasma cutter, some resistor values will need to change. You want to make sure that no electrical signal paths (supplies, gnds, etc.) are shared between your BOB and cutter! Put the entire circuit inside of the cutter, two wires only out to the BOB!

[Torchhead]

From the G540 manual
9) OUTPUTS: The G540 has four general purpose outputs called OUTPUT 0, OUTPUT 1, OUTPUT 2 and OUTPUT
3 on the MAIN TERMINAL BLOCK. They are at Pos 7, Pos 8, Pos 9 and Pos 10 respectively on the terminal block.
These outputs may be used to drive relay coils or for any other purpose. The outputs are rated at 1A and 50VDC
maximum. Connect one end of the load to the output and connect the other end of the load to a positive DC voltage.
This voltage may be the G540 power supply or it may be a separate power supply having a different voltage.

What it means....get a 12VDC coil relay (contact ratings can be anything. Even a small 1A rated contact version will work. Get a 12VDC wallplug power supply can be any amp rating...coil will draw milliamps
Get a diode (1n4002 to 1N4007) Do not try to use the 12V out of your PC. It may not share the same ground as the Gecko Power supply ground
tie the + side of the coil on relay to the + of the 12VDC power supply (Relay Power Supply)
Tie the negative side of the relay to the OUPUT1 terminal on the 12 screw terminal strip (Pos 8 in the G540 manuals)

See page 3 of the g540 manual for a drawing explaining this hookup.

The G540 as 4 driver outputs that are "open collector/Drain" and when activated pull the Pos pin to Power Supply Ground.
Tie the negative of the 12VDC little power supply to the Power Supply GND (pin 12)

Put the diode across the coil of the relay with the cathode (stripe) on the + and the Anode to the - of the coil0 If your relay does not have a + or - marked it will work either way so just designate one as + and the other is -

Now here is the tricky part: In MACH you have to map (MACH) Output1 signal to the G540 OUTPUT 1 (Pin 1) So your MACH output1 would be on Port1 pin 1
If the relay turns on as soon as Mach is out of reset then change the Active Low setting on output1 in MACH to the opposite (green check to red X or vice versa

This is confusing because output1 in MACH is not the same as OUTPUT 1 on the G540 but they have to be connected through the MACH settings and the parallel port

Make sure you have the Spindle CW and CCW activation for ouput1 in MACH3 as M3 (or M03)

Now when MACH is out of reset if you have a screen button that activates output 1 in MACH (flashing on the diagnostic page) and that should fire the relay. An M3 ofr M03 in the G-Code should fire the torch just like the screen button

DO NOT get the diode backwards or the output will be damaged. DO NOT connect the 12VDC+ to ANY thing ON the G540.

SSR's as stated will not work with DC and MUST have current flowing. Most softstart circuits do not have current flowing when you first turn them on so the SSR just sits there.

The problem with a MOSFET SSR is it too must have a voltage source to turn on and they can have polarity. The connections on a plasma to fire the torch do not usually source voltage
They just want a simple swtich closure like you get from a good old electromechanical relay