RPM sensor for sprocket teeth

[Gil47]

When sprocket is rotating,
Can you measure a voltage from signal to com with a multimeter,
Next if the multimeter measures Hz are you seeing something close to 3000Hz.

3000Hz is a fairly fast rate when you need to consider on and off times of the pulse rate.
You say its well within specs, but they always quote fastest, under perfect conditions.

 

[Goody]

I played with this software a while back and I seem to remember there are 2 types of high speed counters HSC and HSCNT - and you can only have one of them in the program. Do you just have one instance of a high speed counter?

I need my laptop to open the software and check (so next week sometime) - but I do remember they were swines to setup and work out

 

[Vic]

Greg640

I have the Red Lion magnetic pickups installed

Why don't you do yourself and everyone else a favor and tell us the model number of the sensor you are using. Red Lion makes several magnetic pickup sensors, most of which are not suitable to wire directly into your PLC Input.
If you want help, you need to give us the information we need to help you.

 

[Greg640]

Magnetic sensor model number

Very sorry for being dumb about this. If anyone still has patience and sympathy, and would like to help, the model number is LMPCC. It is an Open Collector, NPN amplified magnetic sensor. Thank you.

 

[LadderLogic]

It is an Open Collector, NPN amplified magnetic sensor. Thank you.

Well, there you have it. From your original post:

The Input Specification is 24VDC (7ma), with on voltage of 20.4-28.8VDC and off voltage of 6VDC.

Your PLC has a PNP input. You would need to either find a PNP-output sensor or to use a pull-up resistor.

 

[milldrone]

Greg640,

Try a Turck smartplug
http://www.simcotech.com/smartplug.htm

 

[Vic]

Greg640

The easiest way to get your PLC to work with the open collector output of the sensor is to use a pull up resistor. The need to have the On voltage at least 20.4 volts and the sensor's current limiting of 40 mA means the resistor has to be chosen carefully.

Assuming you are using a 24 volt power supply, connect a 490 ohm, 2 watt resistor between the +24 volt supply and the sensor output/PLC input. This should give you about 20.5 volts at the input when the sensor is off and about 4.4 volts at the input when the sensor is on. This meets the specs for the PLC input. After installing the resistor, measure the voltage at the PLC input to confirm everything is working.

Good Luck

 

[Greg640]

Thank you all very much

I am overwhelmed by the generosity, patience and knowledge of you all. Thank you very much.