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Messages - les

Pages: 1
1
General Mach Discussion / Re: DC Servo run away
« on: May 03, 2006, 03:13:15 PM »
Hi

It seems like my problem is fixed .....!

Thanks for the support

Les

2
General Mach Discussion / Re: DC Servo run away
« on: April 30, 2006, 12:50:04 PM »
Hi Wayne

I have used a CD40106 hex inverter chip for x,y and z step/dir into the PIC . Now I get 5v signals that look promising.I will test this tomorrow.
You don't perhaps have a relavant circuit for interfacing the step/dir pulses via optos.

Les

3
General Mach Discussion / Re: DC Servo run away
« on: April 30, 2006, 09:05:02 AM »
Hi Graham & Wayne

I did test the number problem thats fine..!  thanks Graham.
I looked a the step pulses and found the printer port sends out 3.3v for a hi level ,this is in an unstable area because my PIC runs from 5v. I will put a buffer in series to get the step and direction pulse up to 5v.

The noise level is 100mv , this could give a false trigger if the step pulses peaks a 3.3v .....

I will let you know if my idea works....
Thanks.

4
General Mach Discussion / Re: DC Servo run away
« on: April 29, 2006, 06:49:43 PM »
Hi Wayne

Thanks for your quick reply....!

The drives a homemade . I had pcbs made , I am using a Pic18f252 with encoder circuitry , the final output drives a h-bridge mosfet irfz48 x 4 .The 12vdc 10amp motors are connected via shielded cable aswel as limit switches and encoder using separate shield cable and a star point grounding to earth.
The code I wrote using ccs c . I also wrote a vb program that I use to setup the pid and all relavant settings for each drive via RS485 addressable.
I have run tests using the vb program for hours with no errors at all (basically jogging forward 100mm then back repeatedly).Then whether or not with the isolated RS232/RS485 cable plugged in to the PC and drive, I get this run away problem .This happens in random and sometimes not at all.

The step pulses and inrush pulses are clean clean. I seems to happen only when I mill wood in a long straight line of +-300mm.

I am open for any suggestion ....Thanks.

5
General Mach Discussion / DC Servo run away
« on: April 29, 2006, 05:10:24 PM »
While routing on wood ,every now and then the x or y axis runs away over the router table. I have Win XP & Mach2 installed on a 1.3ghz Athlone,I did setup XP according to XP optimization txt file. I have tried with another PC 3Ghz and 500MHz Intel and I have the same problem. I have taken a storage scope to monitor the step pulse and found that there is a inrush of pulses during the moment the x or y axis runs away.These pulses have about 3x the frequency of the normal step pulse.Does anyone know why this could be happeningĀ  .
Thanks
Les

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