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PoKeys / 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?
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?
