Filtering Analog Signal

[Mickey]

Hopefully that's a typo on dbh6's part.

 

[Peter Nachtwey]

Isn't there a built in Lead Lag filter in RS5000?

Hello all,

PLC is a AB control logix 1756-L62 processor

This topic has been covered a million time. Here is one more
http://hydraulicspneumatics.com/con...ion/filter-noise-improve-machine-productivity

 

[dbh6]

@ Bit Bucket 07, you are right the text file used the formula
FV = FV + C(NV - FV), sorry about that it was a typo error on my end.

@ Peter, thanks

 

[gitargr8]

I've used the MAVE function block in the past to help hide the jitter. Pretty simple to set up, and you can determine the size of the averaging array to suit your needs.

 

[Bit_Bucket_07]

No it won't.

I see now that the negative number generated by C(NV-FV) will never be of sufficient magnitude to return a negative result after being added back to the previous value of FV.

Never mind...

 

[dbh6]

You can also use the formula:

FV = FV(C)+UV(1-C)
FV = Filtered Value
C = Constant (0.00 - 0.99)
UV = Unfiltered Value

In the previous formula where we used FV = FV+C(UV-FV) the higher the C value that you used the more it fluctuates, but now with the other formula that i stated above, if you enter a high C value the less it fluctuates. I guess its a matter of personal preference, but i put it out there in case anyone want it that way.

 

[Lancie1]

It is probably so far back in the rear-view mirrors that most have forgotten, but if you have a PLC that only has Integers, you can't use the fractional constant without some manipulation of the formula.

 

[dbh6]

@ Lancie1 you bring up a very good point, i didn't think of that, in the instance where your PLC just has INT's no floating points, how would you manipulate the formula to get your constants as fractional constants between 0.0 & 0.99???

 

[Mickey]

In the old days you would have an implied decimal. (0 to 99) or (0-9)

Move the decimal back when your done. A little rounding off occurs and you have to watch out for values greater then 32767.