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Author Topic: Beware Pokeys 57E is NOT a stand alone BOB  (Read 9694 times)

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Beware Pokeys 57E is NOT a stand alone BOB
« on: June 12, 2016, 09:01:04 PM »
I bought a simple Bridgeport BOSS4 CNC with an old CNC4 Centroid upgrade on it back in September, 2015.  I analyzed the Centroid control system and ordered a Xulifeng BOB from China.  The BOB works great and for $150 plus an old XP computer I had sitting in the closet, I was up and running with Mach3.  The only thing the Xulifeng wouldn't do was send the quadrature encoder signals to Mach3 for position readout.  I realize Mach3 is not closed loop, but it would be good to be able to compare the number of steps requested by Mach3 to that actual number of steps counted off by the encoders.

Enter Pokeys 57E.  Everything I read about it said it had an onboard 3 axis pulse generator and could handle all the Mach3 IO including MANY quadrature encoders.  Sounded like just what I wanted, so I ordered one.  What they DON'T tell you is that the 57E (without the compatible 8 channel CNC add on) won't drive much in the way of loads.  It won't even toggle the opto isolators on the stepper drive cards.  I've ordered opto isolators that will operate on a 1 milliamp input, so hopefully those drop in replacement optos will work.  I'll let folks know when I get them and get a set soldered onto one of the stepper cards.

Next, I tried to get the spindle motor going.  I'm running it with a TECO L150 VFD.  All I needed was a low output for FWD, another for REV and a 10 volt PWM for the speed command.  The Xulifeng had the PWM mapped to a dedicated output which works perfectly and a couple of output pins mapped to Mach2 Output #1 and Output #2 did the trick.  Well, the 57E can map Output #1 and Output #2 to the Fwd and Rev inputs on the VFD, but they won't drive it.  It turns out that whatever drives those pins has to provide a solid ground signal to turn the motor on but that signal must go to a high impedence to turn the motor off.  The 57E supplied enough low drive current to keep the motor on not only in the low state, but also in the high state, or even if you connect the VFD pins directly to the Pokeys 3.3V or 5V supplys!  Those voltages are much lower than the 22V the VFD pulls up to, so enough current flows, even from a 10 volt input, to keep the FWD or REV pins active.  Well great.  Now I'm going to have to build circuitry to make the 57E drive those two pins.

Now for the PWM speed signal.  The 57E has 6 PWM outputs, so surely it will be easy to map the Mach3 PWM speed signal to one of those, right?  I mean, I realize I'm going to have to build circuitry to boost the 3.3 volt PWM from the 57E to a 10V PWM, but hey, I'm used to that by now.  Well guess what?  You Know that big list of IO that comes up when you go to map a Mach3 IO to a 57E pin?  NOWHERE in the 57E manual or the Pulse Engine manual does it give descriptions of what all those choosable IO functions do or how to use them.  I can't find an output that I can identify as the Mach3 PWM output.  Nor can I find an input that looks like it might be a pulse input for my 4 pulses per revolution tachometer on my mill spindle (on the Xulifeng, that signal goes to a dedicated input and it displays the tach signal in the spindle motor RPM box in Mach, just like it is supposed to do).

Well, that is as far as I've gotten to date, but if the other signals I need to run the mill all have to have driver circuits built for them, it just isn't going to be worth it.  Is anyone else having a similar fun time with the 57E?

Offline dude1

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Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #1 on: June 13, 2016, 12:02:47 AM »
did you open a support ticket with pokeys support. PWM is on pins 17 to 22, if you wont it to output step and direction to your stepper drivers or servo driver's you have to set it to 3ch plus IO, it's all in the pin out pick,
you just have to map each pin in march it's quite easy
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #2 on: June 13, 2016, 01:26:16 AM »
I sent Matevz an email with several questions last Tuesday and have not received a response.

I have most of the 57E signals working correctly and verified with an oscilloscope, it's just that the pins won't drive the loads.  The only signal I have not gotten the 57E to output is the PWM speed signal.  I was thinking to use pin 17 if I could figure out which IO to assign to it.  What is the Mach3 PWM signal called?  One might not even need a PWM output from the 57E.  If Mach puts out a high/low of the correct duty cycle for the speed signal, it could simply be mapped to any output pin and that pin would put out the corresponding duty cycle.  The problem is, I can't identify the Mach speed variable.  I can find no documentation or posts that tell what it is called or what DRO number it is or whatever.

The other Mach variable I can't identify is the tach signal input (and probably the pulses per rev setting) that displays in the spindle motor RPM box.  Maybe it's simply not in the 57E list and the device is not programmed to accept a tach signal.

Offline dude1

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Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #3 on: June 13, 2016, 01:46:56 AM »
you need to do it through there support last time I used it, it was 12 hours
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #4 on: June 13, 2016, 10:48:32 AM »
It will drive optocouplers, EL817 and others work without problem, just use schematic in the manual for connecting them. Cant see how a small board with only CPU on it could drive the whole machine... 10V pwm....  it should have been obvious.
And for what it is and for the price, pokeys is unbeatable.
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #5 on: June 13, 2016, 05:22:11 PM »
cant help with pwm output for the spindle as I don't use those but  for the VFD digital inputs you just can't wire them like that.

If you look at the manual https://inverterdrive.com/file/Teco-L510-Manual-EN-v2  on 24th page (3-15) the wiring for the S1 - S4 multifunction inputs is NPN or PNP depending on the model, if using relays this does not matter and you only need to supply 24v or Common from the VFD terminal to the wanted input, only other way that the design will allow is to use a optocoupler transistor output or an Proxy switch NPN or PNP .

You should not try to use pokeys common to switch those inputs on/off and it ofcourse will not work.
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #6 on: June 20, 2016, 11:26:55 PM »
I've gotten some help from support but I still don't have everything working yet.  The data sheet for the EL817 opto mentioned above says it has a 50 mA input current.  How can that work on the 4 mA output current from the 57E?

I ordered a few LDA111 and they worked on the enable and direction signals, but not on the speed pulses.  Turns out the turn off time is way too slow.  The 4 micro second turn on and off time of the EL817 should be fine, but the input current is way too high.  I'm searching now for something that will work for the speed signal.
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #7 on: June 21, 2016, 02:48:29 AM »
Please look to the schematic from the Pokeys manual page 92




and this is my board... al optos are EL817, and working fine

Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #8 on: June 21, 2016, 09:18:30 AM »
Oh, I see I looked at the Absolute Maximum ratings when I got the 50 mA.  The graph in figure 12 does show that 4 mA will turn it on.  I'll get a few of them ordered.

That's quite a breakout board you turned the 57E into!  Can it be purchased somewhere or did you build it yourself?
Re: Beware Pokeys 57E is NOT a stand alone BOB
« Reply #9 on: June 21, 2016, 02:15:16 PM »
Well I needed 4axis 125khz with 35 inputs and 15 outputs all at 24V ( except MPG AB line at 5v ) for my retrofit, and I needed inputs to handle NPN sensors, outputs to be sinking.

When I could not find such an interface board I made one myself with pokeys I got at hand.

These might get to production if my Pokeys starts cooperating so I can test the board on the machine for at least a month.