Micrologix 1500 High Speed Counter

[torygirl]

I need to calculate the rpm of an object that has an encoder on the the shaft and will interface with the 1500. What is a good formula? And also what mode for the counter?

 

[rsdoran]

You didnt state what the PPR was for the encoder...whatever it is once it reaches the pulse per revolution state you have to measure that per minute to reach rpm (revolutions per minute).

Lets say its a 1000 ppr encoder, you need to count every time it reaches 1000 ....ie 1 revolution and time it to see how many revolutions are done per minute..ie rpm

There are numerous ways to do this...show what you have done at this point and more advice can be offered.

 

[PhilipW]

Also we need to know:

1. The range of rpm being measured.

2. The range of how many pulses per second.

3. To what precision (how many decimal places) you need the answer.

4. And how often you need to the answer updated?

All these factors will influence the ultimate solution.

 

[iknowsomeplc]

You can use the HSC Function files of MicroLogix 1500 (it has two of them) in conjunction with the high speed digital inputs on the base module, if you are using an incremental encoder. No need to write any formula.

Please refer the knowledgebase document for more info.

 

[torygirl]

micrologix 1500 high speed counter

The ppr is 500 and the ending result will be a speed reference for a ac drive.
What I was thinking about was this.
rpm x pitch set by the operator and then a
multiplier to get the 0-10 volt output that I need.
What would be the best way to calculate the rpm, if I am counting from the encoder?

 

[iknowsomeplc]

Not sure whether you already gone through the RPM Calculation Example from the MicroLogix 1000 user manual. if not, here is the abstract.