Inscrutable Chinese Edge Finder

[David Bord]

Thanks, really appreciate that!

Can I assume this is for "normally closed" opperation? I have another probe that is set up for normally closed and I think its just wired without any electronics. Is there any risk to doing it this way?

The resistors are easy for me(like in the IH instructions) I'm going to have to have some friends at work help me with your scematic... I dont know how to read them

David

[dkaustin]

I believe this a normally open device. Off the top of my head, I have no idea how to set it up as normally closed, or if it's even possible.

As others have pointed out, if you want to run a normally closed probe, you will need to get the modified xml file from Tormach.

[David Bord]

Originally Posted by dkaustin I believe this a normally open device. Off the top of my head, I have no idea how to set it up as normally closed, or if it's even possible. As others have pointed out, if you want to run a normally closed probe, you will need to get the modified xml file from Tormach.

My toolsetter is setup for NC so I would need to wire this for NC also. I did get the modified XML. Is there any reason to wire resistors for NC operation?

Thanks for the assistance!
David

[justgary]

David -

I'm thinking you can invert the output of the 4N35 with a general-purpose NPN transistor such as a 2N2222 or 2N3904.

Start with dkaustin's most excellent schematic (thanks!) and add the transistor to the output of pin 5 on the 4N35. I'm too lazy to draw a real schematic, or even scan a sheet, so I have attached my e-crayon version. I warn you, it's ugly.

I didn't check the resistor values, but 100 ohms will either work or not... If it were me, I'd probably use 200 ohm or even higher everywhere, including the original schematic. I suspect that both the probe and the Tormach already have limiting resistors, otherwise you would have probably already blown the LED in the probe.

But to answer the question, yes, you need the resistors. By the way, Tormach warns against attaching the DIN input ground to machine ground, hence the need for the opto-isolator. Don't just connect your probe/toolsetter to the DIN input and expect everything to work (or live) unless it is isolated from machine ground.

Regards,

- Just Gary

[Comet_Tom]

NUUBE
You guys are great!