Blinking npn sensor (false triggering?)

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Blinking npn sensor (false triggering?)

Postby KlausLim » Sat Mar 04, 2023 9:09 pm

Hello, I'm having trouble connecting npn sensors to axbb.
When connected, the sensor is constantly triggered.
If you set the homing and limit functions to one, the controller goes into alarm.
At the same time, if you try to press reset, nothing comes out, because the hard lim blinks.
In the program, in the Diag. window, the sensor connection indicators, limits, as well as the home indicator blink.
I use common Chinese sensors without a screen.
The first two photos show how the diodes look on the controller and on the sensor itself during normal operation, when you bring metal to the sensor (the sensors are fine, I connected them after, without a controller, everything works properly).

photo_2023-03-04_23-12-14.jpg
LED on axxb while npn sensor is on

photo_2023-03-04_23-12-15.jpg
LED on the sensor while its on


But when it is in its normal state, as if a false current is passing through it, in the third and fourth photos it is clear that the diode on the controller is on, it does not light brightly, but still it indicates that the sensor triggers, although it shouldn't.

photo_2023-03-04_23-12-16.jpg
LED on axxb must be off

photo_2023-03-04_23-12-15 (2).jpg
LED on the sensor must be off


I tried to connect other sensors, to other ports, nothing.
I tried to connect not npn but pnp way, nothing.
In addition, I tried to connect the sensor to the port on Ucsb, but it does not even detect it)
Perhaps the problem is in the frequency converter, it gives interference, but this is strange, my other frequency converter does not affect the sensors at all, and they are also without a screen.

photo_2023-03-04_23-59-39.jpg
My setup


I hope I explained. :cry:
KlausLim
 
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Joined: Fri Dec 23, 2022 10:02 pm

Re: Blinking npn sensor (false triggering?)

Postby cncdrive » Sun Mar 05, 2023 1:29 am

Your sensor wires are probably picking up EMI noise from the environment (VFD, motor drives etc.)
Try to filter that out, put a capacitor, e.g. 100nF between the AXBB input+ and input- to filter out the high frequency noise.
Also you can add a software filter to the input in the software, the "Inputs debounce" in the I/O settings, set that to a few milliseconds to see if it makes a difference.
But the best is if you also physically filter the noise with the mentioned added capacitor method.
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Re: Blinking npn sensor (false triggering?)

Postby KlausLim » Sun Mar 05, 2023 3:17 pm

cncdrive wrote:Your sensor wires are probably picking up EMI noise from the environment (VFD, motor drives etc.)
Try to filter that out, put a capacitor, e.g. 100nF between the AXBB input+ and input- to filter out the high frequency noise.
Also you can add a software filter to the input in the software, the "Inputs debounce" in the I/O settings, set that to a few milliseconds to see if it makes a difference.
But the best is if you also physically filter the noise with the mentioned added capacitor method.

Thanks, ive put 5ms delay, it worked. For now its ok, soon, ill try the capacitor variant.
Thanks
Also, could you tell me whats the problem with my Ucsb.
Ive connected the same sensor to input i15 on the Ucsb, but the soft does not see it.
Idk what’s wrong.
Maybe its the idc26 cable, ive bought it on amazon.
BD723905-CD6D-4895-AA28-8198DA66D4D4.jpeg

Ive twisted it, so i think wire input goes to another output.
Attachments
852FEFBB-5AF7-4E4E-9A10-6CD2FB749F8F.jpeg
KlausLim
 
Posts: 9
Joined: Fri Dec 23, 2022 10:02 pm

Re: Blinking npn sensor (false triggering?)

Postby cncdrive » Sun Mar 05, 2023 6:36 pm

Maybe your ribbon cable is crimped up in reverse?!
Measure the cable out with a multimeter with continouty measurement, verify that pin 1. goes to pin 1., pin 2. to pin 2. etc. on the 2 sides of the cable between the AXBB-E and the UCSB boards.
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