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leescott

AB analog input card response time too slow compactlogic

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We recently upgraded our machine from an SLC to compactlogix. In the SLC 5/05 we used analog 1746-ni8 cards for pressure and position sensors. When we moved over to the compactlogix 1769 l36erm with 1769-if16c cards we seen issues where the analog values had very little definition accuracy. This can be resolved by changing the filters but then the response time of the card is to slow and we miss data.

All of the relevant code from these sensors are in their own task and ive tried periodic, event and continous tasks but none of this helps.

The strange thing is with the SLC we never seen these issues.

Any ideas how i can improve the reponse time when the filters are set low?

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Just curious, and this may be a dumb question, are you using voltage or current sensors/ transducers?  It looks like on the SLC you were able to choose analog voltage or analog current, the 1769-IF16c is current only.  Just wanted to make sure that you are using the correct module to start with.

 

Other than that, we have multiple 1769-L36ERM with the 1769-IF16c and we use Keyence pressure transducers to monitor pressure/ vacuum and also Visi-track transducers/ counters wired up to High Speed Counters for position on our shot piston tailing rods.  So, we use pretty similar equipment to what you use.

I will check how we have our 1769-IF16c configured and let you know.

I think as long as you are using the correct sensor with the correct module (both current or both voltage) and if your pressure is in the sensing range of your pressure transducer, then it all comes down to the analog scaling.

What type of pressure sensor are you using?  What is the typical pressure range?

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HI,

Its set for current and both the sensors are configured for current also.

We are currently using Sick pressure and postion sensors. If we set the filter to 1365hz then they can read fast enough however if i set the pressures to 16hz and the postions to 50hz the cards response time is greater than 750ms. Which is no good as i need to trigger a data extract at 400ms.

Forgot to mention that i am using the scaling instruction. The pressure sensor is 0 - 95 psi and we require up to 3 decimal places and the postiiton senor is 0 -64mm and we require 2 decimal places.

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