Selection of Counter Module

Dear All,
I read in this forum that to select a counter module we should know the following things.
- The maximum flow rate through your flow meter
- The maximum scan time of your PLC
- The maximum input frequency of your hardware input

Once you work out your maximum flow rate, you can calculate how many pulses per second you will be getting on the input. Then you can calculate the time between pulses.

If the time between pulses is less than (or close to) your maximum PLC scantime, then you will need a high speed counter.

If the number of pulses per second is larger than (or close to) your maximum input frequency of your hardware input, then again, you will need a high speed counter.

If neither of those cases are true, then you do not need a high speed counter and can do it using normal counter logic in the PLC.

Can anybody give me an example to understand completely the aforementioned points?

How do I know how many pulses per second I will be getting on the PLC input?Calculate the time between the pulses. How?
Period of one complete cycle minus the pulse width time

If the number of pulses per second is larger than (or close to) your maximum input frequency of your hardware input, then again, you will need a high speed counter.
What is the maximum input frequency of the hardware?

What is the maximum flow rate of your meter, and how many pulses per unit does the meter produce ?

An example answer would be:

"The system has a maximum flow of 1000 liters per minute, and the flowmeter generates 100 pulses per liter"


Provide as much information and detail as you can.

You did not mention what plc brand is the one you are going to use.
You can avoid all of that, if you use a flowmetter with HART or ethernet communication interface.

After I posted, I looked back through the OP's post history, in which he gives details on several instruments he's trying to use.

I don't have the time to teach a basic instrumentation class.