Hello Guest it is March 28, 2024, 06:17:16 AM

Author Topic: Touch probe wirring and connection  (Read 3548 times)

0 Members and 1 Guest are viewing this topic.

Touch probe wirring and connection
« on: July 26, 2016, 10:04:37 AM »
Hello.

I am trying to connect touch probe to PoKeys CNC board. In manual it says that "external pull-up resistor must be used".
So I draw my idea how to connect the probe and my question to us is, is that correct ?



Image description:
5V - +5V from f.eg."Encoder connector"
Probe inuput - dedicated inputa in "Additional limit switches connector"
GND - ground
Re: Touch probe wirring and connection
« Reply #1 on: July 27, 2016, 03:52:50 PM »
Nobody connect touch probe to PoKeys CNC board ?????
Re: Touch probe wirring and connection
« Reply #2 on: July 28, 2016, 01:04:32 AM »
Don't have a PoKeys, but if it's calling for an external pull-up resistor that looks correct.  I usually see a resistor value of 4.7k specified.  I'm not sure how important the value is, though, as a pull-up resistor simply prevents a direct short when the switch is closed.  In a circuit such as this, the Probe Input will sense a low (GND) when the switch is closed.  When the switch is open, this point will sense the applied voltage (5V in this case) since the resistor is a relatively low value compared to infinite resistance of the open switch contact.  Too high a value of the resistor could result in slightly less than applied voltage but it 10K vs. 4.7K shouldn't make much difference.

Bottom line, if the documentation calls for a specific value.  Otherwise, a value in the range of 4.7 - 10K should work just fine.  But your diagram is right on the money for this application.

Stephen "Highspeed" Kruse
Re: Touch probe wirring and connection
« Reply #3 on: July 28, 2016, 10:31:22 AM »
Thank you, for our anwser.

I connected touch probe to PoKeys board like on a picture and it works whery good.