USB for i/o?

I understand why USB is not used for controlling motion. This topic is NOT related to that.

However, with simple On/Off i/o (such as Coolant, and even Spindle with rudimentary On/Off systems), the delay of the physical action far exceeds any delay that the usb would add. If you HAD to have confirmation, you could (for instance) tie an input switch to a pressure sensor in the coolant. (And that would also serve as a safeguard.)

So, is there currently a way to do that? I know you can bit-bang the serial FTDI chips; has anyone tied one to an M-code?

The reason I'm asking is I have one of those micro boards, and it only has one parallel port. The one slot it has is home for a video card.

Thanks...

yea the usb can be used for general I/O such as switches and relays see posts for Arduinio

You can also look at hidcomp...

hidcomp.sourceforge.net/

And Simple remote pendant...

wiki.linuxcnc.org/cgi-bin/wiki.pl?Simple_Remote_Pendant

Just to name a few.

Rick G

Can a USB I/O work for an auto touch plate ?

A couple questions that concerning the addition of a auto touch plate which enables the machine to touch the plate and set the touch off to Z.0.



1. I am going to use a parallel port for the touch plate signal and I will be using a third one due to the fact that I have the second one dedicated to an MPG, if PCI slots allow can Linuxcnc handle 3?, I would assume so by connecting in the HAL file.
2. When hooking up the wiring to the Parallel port for signal input I.E. I am dedicating pin 1 of the port to the Probe in, what is used as the common? Is it the 5 volts that are used for the limits, relays,..etc

Would this be the info you left the link for Andy?
Thanks

I will be using a third one due to the fact that I have the second one dedicated to an MPG

Unless you have changed your hal files, parport.1 pins 8, 13 and 15 are all free, so you don't need a 3rd parport, unless you are taking that straight to the pendant, not via a BOB

Yes you can have a 3rd parport, PCI slots permitting, the voltage will be whatever the parport is (5v or 3.3v) unless you are using an indirect buffered connection with a higher voltage.
The lower the voltage the more chance of line noise and false readings, so running directly to a parport pin may not be the best option.

If you have noise problems, a simple 12v walmart supply running through the probe, holding closed a small 12v relay which triggers the signal, can be a bomb proof switching method that should eliminate any line noise (unless your probe contacts are 'dirty' and don't break cleanly).

I am using a breakout board with terminal block and socket with a ribbon to the MPG, do you have a pin out handy that would show me where I could grab the voltages?

Using pin 8 going from pin to pin I never could find the 5 vdc

Thanks

rmattioda wrote:

I am using a breakout board with terminal block and socket with a ribbon to the MPG, do you have a pin out handy that would show me where I could grab the voltages?

Using pin 8 going from pin to pin I never could find the 5 vdc

There are plenty of pin out diagrams on the net.

The thing to realise is that pin 8 is normally an OUT pin and that the state of any pin is uncertain until a driver has taken control of the port.

So you need to test with lcnc running, possibly easiest through the HAL Configuration dialog and not get hung up on measuring voltages.