PMDX-126 + tormach probe + electronics help

[andy_con]

so my cnc runs mach3 and it uses the pmdx-126 board.

I have a tormach passive probe, which when hard wired in works perfectly from j15 and gnd on the pmdx.

ive had a very helpful chap make an IR sender and receive for me in an attempt to turn the wired probe into a wireless probe, but were having problems with mach3 and the IR receiver working correctly.

when the probe is hard wired in, all you do is shorty j15 to gnd

we are now switching 5v on and off to j15

are there settings in mach3 or the PMDX I can adjust to get my setup to work?

or do you have to switch j15 to gnd?

[Bob at PMDX]

Yes, your IR received needs to switch the pin 15 input to GND as in the first option above.  The PMDX-126 inputs expect any one of the following kinds of inputs:

- Open circuit or connected to GND, usually for mechanical switches, "NPN" style or "open collector" style sensors

- Open circuit or connected to "+12U" (from the PMDX-126 board) or an external +24VDC power supply, for "PNP" style sensors

- Connected to +5V or GND, usually for sensors with "totem-pole" style outputs (also called TTL or CMOS outputs)


Bob

[andy_con]

ok thanks

we are now switching 5v and GND to j15 (i.e 5v when touching & GND when not touching)

what settings need to be configured in Mach3 for this to work?

[Steve Stallings]

If your IR probe receiver presents a GND when the probe is not triggered
and +5 volts when it is triggered, then it should just work normally.

If your receiver presents GND for probe triggered, then you will need to
configure the probe input in Mach3 for the opposite "Active Low" polarity.
In this case you cannot use the "Probe Merge" option on the PMDX-126.

If your receiver has noise on its output, that will confuse Mach3. This
will be difficult to see unless you have a scope. Mach3 can respond to
noise spikes of as little as 1 uS in some cases.

[andy_con]

 by 'working normally', do you means 'Active High'?

[Steve Stallings]

The comment about "working normally" was not a description of
signal levels but rather a statement that if the probe acted as
described, then probing should be possible with Mach3.

[andy_con]

OK thanks for the reply. Maybe I should re-phrase:
If we are providing +5V to pin 15 when the the probe is touching & GND when the probe is not touching, my questions are:
Should I configure Active High or Active Low in Mach3 ?
How should I set JP5 on the PMDX (ON or OFF) ?
Is there any other setting I should look at ?

[Steve Stallings]

If I may, I prefer to call the conditions of the probe "triggered" and "not triggered".
This is the more common way of describing a digitizing probe such as the Tormach.

When you refer to touching it is easy to confuse this with tool length setting which
operates in the reverse logical manner.

You want your probe input to be Active High (you present +5 volts when the probe
is triggered). Leave the red X in the column labeled Active Low for this input.

You should use the pin 15 input on J12 of the PMDX-126 board.

The jumper at JP5 should be in the Off position. The On position is specifically for
the "Wild Horse" style probes with the LED across the contacts.

You should NOT enable the "Probe Merge" function by setting the DIP switches
on the PMDX-126 board. That is only needed when you have both a digitizing
probe (like the Tormach) and also a tool length touch off plate at the same time.

If you look at the Diagnostics page in Mach, you should see the simulated LED
for the Probe signal light up when you trigger the probe.

One consequence of using an Active High probe signal is that it must always be
connected to the input pin even when not being used. If you wish to physically
remove the probe in order to protect it, you will need to provide a shorting
clip from the pin 15 input to Ground in order to keep the Probe signal inactive
while the probe is disconnected.