Jazz analog input filter

[redhunter]

Hi

I have a project where I have a 4-20mA input and wish to filter it. In the hardware configuration there is a drop down where filter can be chosen from low, med or high. Can't find any info in help section on what the actual filtering is i.e. different rates of filtering between these 3 options.

I am using the 4-20 from a flow meter to control a valve via the Jazz relay outputs and have the situation where the feedback can flicker which can cause the relay to chatter as value changes from one value to next, up or down. In the ladder I have error or hysterisis which works fine but just need to dull down the changing of flow value.

Set up in linerisation is 4-20mA - 0-500 litres per second.

 

Thanks

Craig

[cantcliff]

From what I can find in the general documentation.

 

Low - Last two readings

Medium - Last 4 readings

High - Last 8 readings

 

I'd recommend putting in some form of a de-bounce function to help with the relay chatter.  The High filter will help a bit, but it can still lead to the same problem.

[Flex727]

There is also an additional, separate filter function available if needed.

 

Oops, sorry, I forgot I was in the U90 Ladder forum.

[redhunter]

Cantcliff, by de-bounce do you mean timer functions to stop output going back on until after a set period?

 

Thanks

Craig

[cantcliff]

Craig,

 

Exactly.  Depending on the application it's usually a good idea anyway for mechanical relays.  Solid states it doesn't matter so much as long as whatever you're controlling isn't mechanical either.