PDMX 126 with AM822 drivers and relays.

[dachopper]

JAZZ, most of my faults have been detected by controllers etc, but regarding the 882 error loop..... Do you know, or does anyone know 100% that it is the main motor DC power that needs to be cycled in order to clear the fault?

How are guys doing this? just Cutting the Active line before the ac/dc converter using a low voltage DC press button through a relay?

Redone Schematic, can't decide where to put the E-stop. In the pic, it overrides everything, and turns the pdmx off, but keeps the motion controller on as I don't want to cut that off.

Option 2, is rely on the pdmx safety E-stop circuit, as it will cut power to spindle / motion commands / dust extractor and coolant. then I can on / off the motors if needed to clear fault separately?

I'm normally no where near this machine when it's running, as the jobs are hours long, and I rely on it turning itself off when it faults, not sitting there watching it non stop - as such the e-stop rarely gets used as I'm not there ( No-one is )

[Neale]

How are guys doing this? just Cutting the Active line before the ac/dc converter using a low voltage DC press button through a relay?

My machine uses dual motors/ballscrews on X axis, driven by EM806 (very similar to 882), so I'm a bit paranoid about stopping everything if one of the motors stalls to avoid tearing the gantry apart. To do this, I've wired the fault outputs of drivers in series with e-stop switches (all three of them) so hitting e-stop or fault signal from any driver do the same thing. I also use a safety relay with latching function. Relay is energised by momentary action switch and will drop out on e-stop or fault. Safety relay contacts (a) cut power to second relay which removes a.c. power from driver power supply, (b) cut enable signal to drivers, (c) send signal to motion controller e-stop input (I'm using CSMIO IP/M). So on fault, driver loses power so resetting safety relay (front panel push button) will reapply power and reset driver. So far, all driver faults have been motor stall, when I was trying to drive X a bit too fast. Dropped max rapid speed for X and it's been fine since.

It all depends on your paranoia quotient, but with a largely unattended machine I would probably do something similar - safety relay does the basic "stop everything" actions while the motion controller does other bits and pieces in the background, but I don't rely on it for primary safety. Downside, maybe, is that you have to hit front panel button as well as reset button in Mach3 to restart but that's not a big deal.

One man's view - I'm sure others will do it differently.

[JAZZCNC]

JAZZ, most of my faults have been detected by controllers etc, but regarding the 882 error loop..... Do you know, or does anyone know 100% that it is the main motor DC power that needs to be cycled in order to clear the fault?

You have two choices to clear the Fault. Recycle power to the drives or use the Enable input.
To use the Enable input for a reset you'll need to set it up in the software. Then setup a Drive Reset button which cycles the Enable input.

Like has been suggested most use latching circuit because it's safest approach and kill power so the drives get reset by default so not an issue.

Take your pick.!

[dachopper]

Using the enable input tickles my fancy. So I could run a series wire to a single pin, and send an enable active high/low signal to the drives. Then if the software goes into reset, the enable signal should stop all drives at the same time. Then if I click software reset, that will re-enable all drives up again as it turns enable back on.

[Neale]

I'm sure that would work but...

If a drive fault happens, you've lost position, or don't know if you have lost position which is almost as bad. So you will probably have to rehome, rewind the gcode to an appropriate point, and then restart. Pushing an extra button on the control panel is the least of the issues. But I don't know exactly how you plan to use the machine so maybe that's not relevant.

[JAZZCNC]

Again you are relying on software which isn't good or safe.

Not sure why your resistant to using Master Latching relay system because this could handle all you need and more. When fault or E-stop occurs it's single Reset button when a fault is cleared. If you want the Software to be reset at the same time that could also be done but wouldn't advise it.

Like Neale says any Fault or even software Reset which drops power to the drives or releases Motor hold will result in Re-homing so compromising your safety to save one button press just isn't sensible IMO.

[dachopper]

Ok, so by a master latching relay, how can I mechanize it? I assume your talking about the AC power that powers the motors, spindle, and coolant being physically cut by a relay, when e-stop or fault conditions are detected and staying latched, but how can I achieve this using fault signal - like you say without software?

Neale - the relays on my PDMX perform all the functions of your latching safety relay, except they are not latched ( Unless activated by pressing the latching E-stop switch )

[JAZZCNC]

Ok, so by a master latching relay, how can I mechanize it? I assume your talking about the AC power that powers the motors, spindle, and coolant being physically cut by a relay, when e-stop or fault conditions are detected and staying latched, but how can I achieve this using fault signal - like you say without software?

Creating latching relay is easy you just route the coil power thru one of the NO contacts before connecting to the coil. This breaks the circuit until the Momentary reset button is pressed. This Momentary button goes between power and the coil so when pressed powers the Relay coil which close the NO contact allowing power to flow to the coil, relay then remains latched until something breaks the latch. That could be E-stop, limits or fault signal.

You then use any remaining Contacts on the relays to operate or send signals to things that need them. What you control or inform is upto to you but no where in this does software control anything. It just gets informed whats happened so can stop code or flash messages etc.

Also don't confuse an E-stop which latches when pressed with a Latching Relay because they are not the same. The PMDX relays are just plain relays and soon as the E-stop is released they will become active again. Neils safety relay won't do that. Like wise if any of those contacts melt down closed they will Fail ON Neils Safety relay will sense this and won't allow restart.

[m_c]

You need to split the power into two distinct groups. One being control power, the other being motion power.

Control power you generally want to remain permanently on, and powers things like the controller, input sensors, buttons, etc. Basically anything that being still active isn't going to cause motion.

Motion power is anything that powers things that move i.e. stepper drives, spindles, solenoids. Motion power you want to kill as quickly as practical in the event of an E-stop.

If you don't want to go to the expense of using a higher voltage for controls, use a 5V version of the relay I linked to previously, and do what Jazz said to create a latch. That way you can use the contact that's providing the latch, to also control the E-stop input on the BOB.

[Neale]

...and to get the fault signal to trip the latching relay, you can wire the fault outputs from the drivers in series with the estop switches, and any fault output or estop operation will trip the relay. I have three driver fault outputs and three estop switches all wired in series and it works a treat. It's that easy. The set of "switches" are wired into the supply to the relay and you just have to watch the polarities of the fault outputs when you wire them in.