Analog filter for micro 1000

Join Date
Apr 2006
Location
nd
Posts
4
Newbie here. Went through the bouncy analog signal threads for SLC 5 series and got some good tips, but I also have micrologix that doesn't have the compute function. Any ideas for the 1000 filter?
 
no scale with parameters either. There was a ffl ffu example I saw in another thread but it didn't work right. It would hit 32768 and fault the processor. I unlatched the overflow trap so it wouldn't fault and played around with it alittle but no luck. Any other ideas?
 
The filtering can be done with integer math. Just use a divide by integer number of points instead of the multiply by a float.

Attached is a PDF showing how we implemented the same filtering algorithm in AutomationDirect.com with just interger math.

Scaling can also be done with four function math - here is the theory:

For any unit conversion on any PLC you can use four function math with the following, which
asumes integer math:
DataOffset = Data in input register at 4 mA (or zero analog signal of whatever range
- for example 0 VDC on a 0-10 VDC transmitter)
DataSPan = Data at 20 mA - Data @ 4 mA
FACTOR = arbitrary factor (multiple of 10) needed to get proper resolution and accuracy
EU = Engineering Units x FACTOR
EUOffset = Engineering Units @ 4 mA x FACTOR
EUSpan = (Engineering Units @ 20 mA - Engineering
Units @ 4 mA) x FACTOR
DATA = Actual data reading in input register
EU = ((EUSpan x (DATA - DataOffset))/DataSpan) + EUOffset
ProcessValue = EU / FACTOR
For Example, 0-60 psig from 4-20 mA with resolution of 0.1 psig:
FACTOR = 10
Data @ 4 mA = 6240
Data @ 20 mA = 31208
DataOffset = 6240
DataSpan = 31208 - 6240 = 24968
EUOffset = 0 x 10 = 0
EUSpan = (60 - 0) x 10 = 600
DATA = 18975
EU = ((600 x (18975 - 6240)) / 24968) + 0 = 306
Process Value = 306 / 10 = 30.6 psig


And here is an example.
 
This logic does nothing. I don't know where to start. What's the n7:46 100 times 100? And the 264 divided by 10000? Tell me this is a joke.
 
If it is a joke, it is being played by Rockwell, not me.

RTFM - specifically the SCL function description. This logic works - the system I extracted it from has been running for a few years now.
 

Similar Topics

Hi! I like to ask is there a way i can filter my analog input?
Replies
1
Views
1,089
I have a 4-20 ultrasonic sensor on an oil tank. I am getting spikes that I would like to get rid of. Have tried this but I get 1.#QNAN. V18, no...
Replies
28
Views
12,644
This sounds like a stupid question, but I can't find an answer anywhere. I realize that a lower filter freq on an analog input channel results in...
Replies
10
Views
3,525
I have an analog signal that has a small amount of noise. It is on an RX3I PLC and the analog in module (IC693ALG442) does not have filter...
Replies
35
Views
9,339
Hey fellas, I've got some Point I/O analog inputs (1734-IE8C) that I would like to filter. FYI, this is for some flow meters. The raw...
Replies
9
Views
7,380
Back
Top Bottom