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Index
« on: February 27, 2020, 03:04:17 PM »
How to wire up a Reflective Object Sensor (OPBA) using the index function in Mac3 to read actual rev. of the spindle. I have input 11 on the BOB available for the task.
I will be most grateful for any help.
Re: Index
« Reply #1 on: February 28, 2020, 06:09:23 AM »
Is it possible to do it? Has anybody done it and if so, how to?

Offline TPS

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Re: Index
« Reply #2 on: February 28, 2020, 08:26:16 AM »
if you give us some more Information about your sensor and BOB, maybe?
anything is possible, just try it.
if you find some mistakes, in my bad bavarian english,they are yours.
Re: Index
« Reply #3 on: February 28, 2020, 09:13:28 AM »
The sensor is OPB606A and data is on the net. I have newly installed a new BOB from CNC4PC: C11GR9-S3578-46. I do not need information on how to mount the sensor, only the wiring.

Offline TPS

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anything is possible, just try it.
if you find some mistakes, in my bad bavarian english,they are yours.
Re: Index
« Reply #5 on: February 28, 2020, 04:14:48 PM »
TPS
Thanks a lott. Here is a lot of information, lucky I may find find a solution.
THANKS

Offline MN300

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Re: Index
« Reply #6 on: February 29, 2020, 08:06:00 AM »
The OPB606A is specified as having an output of 500 uA under the test conditions. This is barely enough to drive the 10K resistor shown in the diagram found in the link TPS provided. Your conditions will be less than ideal as dirt and film build up on the sensor and the shaft. Also your reflector is curved, reducing the effective area.

The OPB607A uses a Darlington photo transistor and has a much higher output - up to 25 mA (50 times more).

The diagram's R1 which sets the diode current is a bit low. Nominal current is 20 mA, 100 ohms would result in 33 mA. 150 ohms would be a safer choice. You could overdrive the diode but run the risk of overheating and failure.

Your reflective surface should be 50% white and 50% matte black, a bare shaft may reflect light.

An open photo sensor is a high maintenance item. It will take frequent cleaning to keep it running.
Re: Index
« Reply #7 on: February 29, 2020, 08:34:29 AM »
AHA, that may be the problem. I have tested the OPB606A on the bench and get the reading 4,56 and 0,15 volt witch should be ok, but when installed in the machine the numbers in the RPM display in the Mach run page flickers. Also the green index button behaves unstable.
Will try to get a OPB607A. Or do you recommend a different solution? 

Offline MN300

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Re: Index
« Reply #8 on: February 29, 2020, 09:08:48 AM »
A magnetic solution such as a hall effect sensor wouldn't suffer from contamination but the part you attach to the shaft is more difficult to make.
Here is a example of a vane sensor  https://www.digikey.com/product-detail/en/tt-electronics-optek-technology/OHB900/365-1002-ND/374780
You would have to make a disk with slots. One vane would not be balanced so there would need to be two. I image someone could make a one vane design with a counterweight but that's way above my pay grade.
You have started on the optical route, it will be informative to hear how successful that is for your application.
Re: Index
« Reply #9 on: March 01, 2020, 05:43:26 AM »
I have ordered both "hall effect sensor" and the OPB607A sensor but it will take some time before I get it, I will keep you informed.
In the meantime how is the wiring for the "hall sensor" and can I use the same resistors (150 ohm and 10 Kohm) for the optical solution using the OPB607A ?
« Last Edit: March 01, 2020, 05:45:36 AM by sivtek »