Trigger Issue Proximity Sensor

Hi everyone,

I am trying to run an engine with a proximity sensor of the crankshaft with a 36-1 tooth disc. I am not getting any RPM reading unfortunately. When using the scope funtion during cranking there is a nice clear square wave signal. However, due to the voltage drop over the proximity sensor the signal goes between 7V and 3V.

Does the Link ECU expect the signal to go to 0V? If it does can the threshold be adjusted at all?

I have added a screenshot of the scope signal as well.

Thanks for the help,

Rob

Hall effect sensor thresholds are fixed in Link ECU's, 1.5V on the rising edge and 1.0V on the falling - so it must fall below 1.0V to be considered a tooth. Why doesnt it go to zero volt would be the question though? They are typically a NPN type device so it should go to near zero volt when a tooth is present. Is it not connected to sensor ground? Does it behave different with the pull-up turned off?

What is the part number for it? many industrial prox sensors arent suitable as they will invert at a certain speed.

Hi Adam,

Thanks for the reply! It is a 2-wire proximity sensor. I checked the datasheet and it states that a voltage drop over the sensor up to 4V would be normal. So not much to do about that bit.

Also, thanks for pointing out the speed requirement. Turns out it would only have been good up to 2000 Hz anyway. I have a Bosch VR sensor arriving Monday morning so hopefully that will sort things out.

Thanks for the help!