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Author Topic: 8 position lathe toolchanger  (Read 7845 times)

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Re: 8 position lathe toolchanger
« Reply #10 on: January 29, 2017, 09:09:02 AM »
Richard

Just realised I missed off the resistor values in my circuit diagram. From my research the 270 Ohms resistor is a current limiting resistor and if you leave it out

you will fry the sensor (suggested range 180 Ohm to 2.1 kohm) . The 270 kohm resistor is a pull up resistor with suggest range (2 kohm to 470 kohm)

This is the extract from the site where I got the info (let's make robots)

 "Finding the exact values needed to make the photo interrupter work is a bit tricky.

Play with different values of both resistors to get a good response. The idea is to have high enough voltage when the slot is blocked to register as a HI input but also

be close to ground when the slot is blocked. If it doesn't get to ground then either the current - limiting resistor is too strong or the pull up resistor is too weak.

If the signal line doesn't get high enough, you may need to lower the resistance on the pull up resistor."


The values I chose seem to work well for me. Hope this helps.

Also I don't think my explanation of the system logic was clear.

When configuring pokeys to accept these 4 sensors they should be assigned as INPUTS 1 to 4  (not outputs)

I have tweaked the turret position diagram and added truth table for clarity.

I have also added the brain for completeness.

Please note that bugs contained within the brain software impose certain restrictions on it's use

One of these I found was that the program would only work if it was short enough to fill one page only.

So to shorten the number of lines of the program some of the superfluous statements were removed.

ie tool position 2 is uniquely described by the conditions Input 3 And Input 4  are zero's.

No other tool position has that condition

program lines containing Input 1 and Input 2 can be removed.

Cheers George   
Re: 8 position lathe toolchanger
« Reply #11 on: January 30, 2017, 10:20:37 AM »
Thanks Bigwing