Research for proximity sensors
The Omron proximity switches that are going to be implemented are 12V/24V E2E-X5MF2 which are PNP-NC (normally closed). Data sheet here
They were bought to replace some surplus E2E-X2ME1-M1 which are NPN - NO (normally open).
The Omron proximity switches that are going to be implemented are 12V/24V E2E-X5MF2 which are PNP-NC (normally closed). Data sheet here
They were bought to replace some surplus E2E-X2ME1-M1 which are NPN - NO (normally open).
The normally closed configuration is far easier to implement with the cnc4pc breakout board.
Circuit diagram for hookup:
My pin assignments for future reference:
Sensor cable > Cable strand # > task (Control box wire colour)
blue > 1 > 0V (blue)
brown > 2 > +24V (yellow)
black > 3 > signal (green)
Connecting 3-wire PNP outputs in series:
Note from www.ab.com:
Series connection of 3-wire PNP output devices requires each device in the series to supply power to the next device with the last device in the chain supplying power to the load. Because each device supplies power to the next, response time is equal to the response time of the first sensor plus the sum of the turn on times of the others. The output of each sensor must be capable of supplying the peak load currents of subsequent sensors plus the current of the load. To overcome the internal supply capacitance of subsequent sensors, a low value (10 ohm) resistor is sometimes required in series with each.
A few brackets and new holes in the column later and here is one half of the Z axis. I can get away with using only a single sensor with two adjustable stops made from stainless rod. I milled a flat on the sections of rod so that the sensor "sees" more material as it crosses the threshold; perhaps this is not necessary (but it looks nice).
The next question is how to splice the sensor cables to extensions. The location of the connections is going to be within the work area of the mill which means, if coolant is going to be used, that they have to be watertight. One possibility for this are TE MiniSeal Splices.
Available from Mouser at a mere $2 a pop!
http://ca.mouser.com/_/?Keyword=miniseal+wire+splice&FS=True
The D-436-36 model is for 20-26 AWG wire.
Circuit diagram for hookup:
My pin assignments for future reference:
Sensor cable > Cable strand # > task (Control box wire colour)
blue > 1 > 0V (blue)
brown > 2 > +24V (yellow)
black > 3 > signal (green)
Connecting 3-wire PNP outputs in series:
Note from www.ab.com:
Series connection of 3-wire PNP output devices requires each device in the series to supply power to the next device with the last device in the chain supplying power to the load. Because each device supplies power to the next, response time is equal to the response time of the first sensor plus the sum of the turn on times of the others. The output of each sensor must be capable of supplying the peak load currents of subsequent sensors plus the current of the load. To overcome the internal supply capacitance of subsequent sensors, a low value (10 ohm) resistor is sometimes required in series with each.
A few brackets and new holes in the column later and here is one half of the Z axis. I can get away with using only a single sensor with two adjustable stops made from stainless rod. I milled a flat on the sections of rod so that the sensor "sees" more material as it crosses the threshold; perhaps this is not necessary (but it looks nice).
In the bottom if the frame below you can see piece of green masking tape. This is a little trick I learned from some conservation staff in a museum where, for obvious reasons, dust control is a big deal. Whenever they drilled into a wall they would tape a pouch made from scrap paper or newspaper right underneath the hole to catch the dust before it fell onto the floor. No cleanup afterwards [hand slap to the forehead]!!!
The next question is how to splice the sensor cables to extensions. The location of the connections is going to be within the work area of the mill which means, if coolant is going to be used, that they have to be watertight. One possibility for this are TE MiniSeal Splices.
Available from Mouser at a mere $2 a pop!
http://ca.mouser.com/_/?Keyword=miniseal+wire+splice&FS=True
The D-436-36 model is for 20-26 AWG wire.
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