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TechJunki

Simple Encoder

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I have a winder application that I need to measure speed and yardage on the roll. Has anyone had any experience interfacing a simple encoder such as a pulse encoder in to a high speed counter module for the logix and measuring speed and yardage. The winder currently is just an AC motor with a manual speed control, no feedback whatsoever. But I do have a contrologix PLC available and empty slots to accomidate a specialty card if necessary. What is the recommended practice or what have the rest of you been using for this type of application. Encoder Type?? Logix Module?? Thanks for any info..

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What kind of RPM are you talking about? You need to make sure that the PPR (pulses per rev) times the RPM does not exceed the Frequency of the High Speed Counter module that you get.

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I've used the 1769-HSC numerous times and the 1756-HSC once. I'm not as familiar with it but I know the the 1769-HSC You can configure it for a rate or measurement, but not both. I normally configure for measurement and use a periodic task or timer to sample for the rate. Any encoder with a 5VDC open collector or DLD output will work. Also, if you happen to have Devicenet on it, you might look at the Flex I/O HSC as a more economical solution. EDIT - I just did a quick refresher of the 1756-HSC and it looks like it only does measurement so you use a periodic task for the rate. I think you will find it very easy

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I think the Spectrum counter cards are head and shoulders above the AB offerings. I have not used one with the CLX platform, but have many in service on the SLC platform. (The SLC cards are cheaper too!, not sure about the CLX ones) Multi-channel, and you can have rate and measurement. I would take a look and perhaps contact their tech service people, they have always been very helpful. http://www.spectrumcontrols.com/ab-1756_CTR8.htm

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TW are you sure? I think I have 1756HSC doing rate. In mode 4. I am not in the shop but Monday I can verify.

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Yes, but can you do rate and measurement at the same time? I don't have a 1756-HSC to test on.

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TW You are correct. tht channel will not do both. Are you saying to make your own Rate just have a periodic task run and use the value to calculate the Rate while doing Measurment? That sounds like like it would work and kill 2 birds with 1 stone.

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TW, do you have a sample of the periodic code you are using for your rate measurment you care to share as I am now beginning to implement this? Thanks for all the help with this.........

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Hi Techjunki I do have an example of this but it's not on this computer and I'm getting ready to run out the door. It is a cleaned up version of the sample on page E-28 of the Micrologix 1000 manual using a periodic task instead of timer. http://literature.rockwellautomation.com/i...um003_-en-p.pdf I will try to post it this evening but as I recall the example can be streamline to two clean rungs in a periodic task. I thought it had already been posted before but did a quick search and couldn't find it TW

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Thanks I'll take a look at the pdf..

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