G-REX wiring

[Lost Tourist]

I have recently bought a second hand Hercus PC-200 lathe from ebay which requires new controls (the old controls recommended DOS 3.3 and apparently even then it didn't have the processing power to do accel and decel curves)
I have lurked around here for a while and worked out that i will probably be ok with a Grex running 3 x G320's however what i haven't been able to find is a wiring diagram for the inter-connections, so i have started my own.
Attached is a draft of my intended wiring, the remaining issues i was wondering about was how are the limit switches supposed to be wired and do i need the opto-isolators between the encoder and G-Rex (as i remember reading somewhere)
I have an e'stop on the machine that i will also wire in as well as a pendant but they're for later.

Any comments would be appreciated.

Thanks.

[eat]

this is somthing that is needed.
I was looking for a wile recently
on mine so far I just have the encoders connected to the drives and all that is connected to the grex from the drives is
the step and direction wires from each drive to the step and direction axis connections on the G-Rex

I amjust ready to start motor tuning so
I cant say that I have a running setup yet
but I called them and they told me that was all I needed to connect
that and the 5 volt from the grex to the common
on the drives to supply the power

I tried to take a picture of what i have so far but my camera decided to die tonight.

also they recommended a capacitor digi-key part number P10874-nd connected to the connection 1 and 2 on the drives the (power ground) and the (+ 18 to 80)
if the wires are over 18 inches long from the power supply
mine is about 24

I hope this was some help

[fbmstar]

hey lost tourist, I'm also a long time lurker for the most part and in need of a g-rex g100 wiring diagram. Have you confirmed any part(s) of this diagram?

[Lost Tourist]

Nothing confirmed yet.

[Runner4404spd]

just curious but why do you need to parallel up the geck320 encoder wiring with the GREX encoder wiring? wouldn't it be sufficient to only wiring the encoder to the GREX? after all the GREX is relaying the step and direction signals now not the G320.

[ger21]

Actually, the G320's won't work without the encoder signals, and the G100 can't do anything with them, as far as I know. Or is the G100 encoder postion available to Mach3 through the plugin?

[Lost Tourist]

Runner4404spd,

To the best of my lurker knowledge it is a fundamental requirement that the encoders be fed back to the 320's as the GREX only sends a step and direction "request" not "instructions", the GREX says move 2 steps CW and then the 320 has to calculate the control signals to actually move the motor based on feedback to the 320. If the 320 didn't get any feedback it would never know when it had achieved the position as the GREX can't tell it as it only sends requests for movement (in actual fact i think the GREX and 320 talk back on forth but i think the messages are GREX sends new step and direction and the 320 sends back move complete)

The whole function of the GREX, as i understand things, is that it produces better step and direction signals.

I think sending the encoders the GREX will tighten up the tolerances as currently errors less the 320's error tolerance won't be noticed as the only error signal the 320's provide is in tolerance/ out tolerance.

[fbmstar]

I noticed that you don't have the +5V "common" on the G320's hooked to anything. Do the drives not need it since it is hooked up via the G100? You wouldn't happen to know why it's there in the first place, would you?

Also, could you explain the function of the opto-isolators? What would you forsee happening if they were not present?

Thanks,

Brian

[Lost Tourist]

Well spotted Brian,

Poking around a bit and i think that terminal needs to be hooked to +5V. It's there as part of the step direction circuitry, these signals need to be relative to something so they are relative to the common voltage signal. (they are signalled when lower than +5v)

I'm not convinced the opto-isolators are "required" however in this thread G320 and Grex Encoder and Err/Res Hookup...
Mariss is stated as saying you should do it (and apparently Mariss is the man when it comes to Geckos) I suspect it is just good practise as using the opto-isolators makes it significantly more unlikely that you will manage to fry your 320 and send your motor power to the computer turning your computer insides to slag. If nothing ever goes wrong you can probably get away without them but what are the odds that's going to keep happening.

[fbmstar]

well, i couldn't wait any longer and decided to start hooking wires up. I'll give you a step by step progress of my day so all may see what doesn't and what will work.

I started with just 1 driver and followed your (lost tourist's) wiring diagram to a T (minus the opto isolated circuits). The drives just remained in a fault state.

So i decided to step back and hook up only the encoder to the driver which left only step and dir going from the G-rex to the driver. This did not work either. I then hooked up the +5 common on the driver to the +5V in the power section (under the "USB") on the Grex. This still did not work.

At this point, i remembered or reread that the ERR/RES on the driver needs to be hooked to the ECN+ on the driver. This ended up working for one drive.

I then hooked up another driver w/ the same setup, and shared the +5V on the G-rex for both drivers common input. This did not work, both motors would move when jogging only one.

Finally, i hooked up the +5V (right next to the Step output on the G-rex for each axis, which i think is for the encoder?) to the to the common on the driver. This seemed to work.

So, as of now, i have the encoders only going to the drivers, and step, dir, and +5V on the G-rex going to the drivers. i have 2 "fully" functional axis now, but don't think this is the way i will leave the setup.

I hope all that made sense, but i'm in a rush and need to run off.

Brian

[Lost Tourist]

Brian,

I too am thinking about starting to wire things up but i'm a bit behind you as i still need to install the transformer.

If i understand you correctly your circuit should now look like the attached.

I assume you are using mach3 with the G100 plugin? If so did you have any trouble mapping the outputs from Mach3 to the G100?

[juan30]

Hello Lost tourist,

I`m reading this threat with most aroused curiosity.
Hope you find an solution. and maybe i can use it

I have other servo`s then yours, but I have the G320

Juan