I spent one full day trying to get the touch plate to work and I was not successful.   I read the entire other thread on the subject and tried everything.   So here is what I followed, one wire of the touch plate on port 2 pin 13 with a  4.7k resistor on pin 13 and 5v.   I have the ESS set to low.  Without anything touching the touch plate wires the probe led on the diagnostic is illuminated.   I tired other resistors with the same result.  The only way I can get the led on the diagnostic screen to go out is by running a jumper from the 5v to pin 13.    With the 5v running to pin 13 the touch probe will work until it hits and then the ESS loses communication due to power interruption which I am assuming is probably not good for the board.    Also without any wires connected to any pins when pin 13 is set to low the led on the diagnostic board is lit.  If I set the ESS pin 13 to high the probe led on the diagnostic screen works perfect when putting 5v to pin 13 but obviously this won't work.

I am using the C25 BOB and an external power supply.  If anybody has any ideas or if more information is needed let me know please.

Hi,
you in fact have to interface to the BoB not the ESS, or at least not directly.
Try a pull up resistor of 1kOhm.

Craig

Hi,
page 2 of the C25 manual shows the input circuit of a generalised input pin. It has a 4.7kOhm pull down
resistor. You'll need a pull up of 1 kOhm or less to pull it high.

Craig

Ok thank you for the reply, I do realize that I mispoke about the ess and C25.  I'm not a wiz with electronics (I am an extra class ham radio operator though)  so bare with me.  Ok so you say I need a 1k resistor as a pull up resistor and I am guessing that would go between my pin 13 and the 5v?   I think I actually tried that with a 1k resistor but it still did not work.    If that is not what you meant let me know.  Thanks.  I will try again to figure this out tomorrow and post a little more detail and some photos if I can.

Hi,

I am guessing that would go between my pin 13 and the 5v?

Yes.

Craig

Solved!!   A 100 ohm resistor is what it took to make it work.  I just kept going down in size and thats the one that did it.  Thanks for the replies and help.

John

Hi,
if thatsthe minimum something is fishy.

5V/100 Ohm = 50mA, and 50mA sounds too high to me, 5mA or 1kOhm should be plenty.

Craig

Well as I said I am no electronics wizard but I tried a 1k, 470ohm, and one more but it took a 100ohm to get it to work.    I am just happy that it works and it works well.     On a positive note having to try to find the answer I have learned more about my machine and Mach 4 and probing.  So my day was not a waste.

Hi,
50mA is I believe too much and there is a risk that there is a fault or some misapplication happening
and failure may result.

Craig

Ok, what is the absolute minimum ohm resistor you would think would be safe?   I'll try it and see what happens.