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Author Topic: Mach3 w/ new UC100 No Limit switches recognized  (Read 1921 times)

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Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #10 on: June 08, 2017, 08:33:47 AM »
my BOB is fed with a 24VDC PS.  they are fed from same.
the sensors are labeled PN SN04-N, found their specs.  Supply is 5-36VDC, 0V NPN N.O. output.
when I put metal in front of them, their signal line goes from 9.3V down to 0.7v.  Which "SHOULD" be enough to detect to zero for the Mach.  BUT!!!
The other channels drop by from 9.3 down to 8.3 simultaneous.  Even though I am not activating that sensor.

So, I don't know the history of the sensors by previous owners that hacked.  I am a electrical engineer and been doing sensors for 25yrs.  So, i understand and know what they SHOULD be doing.
And I know that these are acting weird.  So fairly convinced that the issues are in the sensors.  I will create the 3 switches w/ microswitches to GND and diagnose from there out.
Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #11 on: June 08, 2017, 08:51:35 AM »
Hi,
where are you measuring your 9V?. If its at the UC100 input pin then you risk wrecking it.

I suspect that as one input goes low then the reverse current flowing into the UC100 inputs is somewhat reduced therefore the remaining
pins achieve somewhat closer to 5V. If you are injecting current into the UC100 inputs STOP! The input gate of the Schmitt triggers are likely
protected by diodes from overdrive. Any substantial current will blow them open with unknown consequences for operation of the gate.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #12 on: June 08, 2017, 12:36:23 PM »
Tonight, will be testing with DRY mechanical switches.  No NPN NO circuits.
Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #13 on: June 09, 2017, 06:32:39 AM »
Well, a couple more steps of diagnostics.
the sensor inputs of the BOB are free hanging around 8-9V when NOTHING is connected.   I tested each limit with a simple wire to GND.  XYZ worked fine reading all the way to Mach3.  So, system works.
The prox sensors were being powered by the 8-9V sensor voltage backfeeding through the inputs.  The sensors are supposed to be powered by "source" power.  They were getting their only voltage through the signal wire.  Their power was connected to the 5V on the BOB which was putting out nothing.  So, tonight, move power source to the 24V source.  See if they work now.

This "being powered through the signal" problem explains why if it was triggered by a proximity to metal, the other 2 sensors would drop their voltage too. 

Worst case: new BOB;
Best case: 5V is bad and have to power them from another source.

Either way, I'm closer now than ever before.

Offline kolias

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Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #14 on: June 09, 2017, 10:00:20 AM »
Here is something to think about

Once I had a timer connected to my cnc to indicate the length of time the cnc was working. I did some changes and then the timer stop working. By accident I discovered the timer was taking the power (POS & NEG) in the PSU from the same terminals like my drivers. I removed the timer terminals to another free location on the PSU and voila, the timer was now working. Weird but did the trick
Nicolas
Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #15 on: June 12, 2017, 06:19:43 AM »
the 5V supplies on the BOB were OUT.  So, I built a voltage divider for the 24V supply to the BOB.  Powered the sensors at 10VDC.  They worked perfectly!!!  Problem solved!!
Re: Mach3 w/ new UC100 No Limit switches recognized
« Reply #16 on: June 13, 2017, 07:57:36 AM »
I am using the UC100 through a BOB.  The BOB is where I "Was" getting the 5v power for the sensors.  THey are recommended to be 8vdc minimum up to 30vdc.
SO, my divider got me to 10V for the sensors.  The signal from the sensors to the BOB inputs pulls the ~9v down to 0.7vdc when sensor is activated.  Doesn't the BOB isolate that from the UC100?  I know its works currently.  I found that the BOB was putting the 9.3V OUT of the inputs.  if you pull that down to 0, then the Mach3 registers an output.