machine stops when homing

[cropwell]

I used to use proximity sensors on 24V straight into the pin on the cheapo BOBs There is a 10K R inside a lot of them so it should only put about 2.4mA into the BOB you can check this by putting your meter on mA range and connecting between the black wire sensor and ground. and see what current it draws. (at your own risk of course)

If you use an external 10k connected to the sensor output, and measure from the other end of the resistor you won't blow the sensor up and you can take that into account in your calculations. I use them straight into the BoB with a 12v supply to the sensor with no problems.
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I have just set up a lj12a3-4-z/bx on the breadboard.
Using a 30v supply the output shows 30v and drops to zero when triggered. BUT the current through a 10k load is 6mA, and without the 10k it is still 6mA. So there must be current limitation.

Then I tried it at 15v and it is the same but 3mA current.