Encoder Conversions

sgates · Apr 30, 2008

I thank all of you for your past help and appreciate your patience with my questions. This is most likely a simple question but I need help; due to the fact I have not programmed encoder units. Two weeks ago, my employer informed me that I was to program a control system for a Flywheel generator. Everything was going well until I was told the system had an encoder to tell the system that the generator was at the right frequency. My question is how to I convert the encoder data to a frequency output date. The system I am using is an Allen Bradley 1769-L35E revision 16 with a 1769-HSC module. Please if anyone could help, I have four days left to make it work.

ndzied1 · Apr 30, 2008

Not sure how easy or hard configuration of this bad boy is but once you have it configured, getting the frequency should be easy.

Here's a blurb from the manual (Publication 1769-UM006A-EN-P - March 2002)

Cyclic Rate Calculation Method (Current Rate)
The module continuously calculates rates for each of its four possible
counters, regardless of operational mode (e.g. up/down count). The
32-bit signed integer rate from each counter is reported in the
Ctr[n].CurrentRate words of the Input Array.
In this method, the rates are calculated at the end of a counter’s
configured cycle time. This is configured via the
CtrnCyclicRateUpdateTime configuration word/menu. Valid entries
are +1 to 32767 milliseconds. The number of net counts, net change in
Ctr[n].CurrentCount, during that period is converted into a rate value,
providing an average pulse rate.
The generalized rate calculation is: Rate = D count/ D time.
The cyclic method is better suited to high pulse rates.

Encoder Conversions

sgates

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ndzied1

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