ML1100, Averaging/Filtering Suggestions

Hi,
We have a ML1100 with what appears to be a very noisy signal at normal operating speed.
Am trying to think of the best way to deal with this, whether it should be software or electrical.

If I were to do it in software, should I use a filter or averaging?

An example of how often/much it jumps is say, from 7.2 -> 8.9 every 5-10 seconds.

The best bet is to remove the source of the noise if you can.
The next best is to use an isolator on the input.
Below I show what I have used, from memory, to remove spikes that appear on top of otherwise steady readings.

I've always liked this format...
FILTERED_SIGNAL = K * ( SIGNAL - FILTERED_SIGNAL ) + FILTERED_SIGNAL
K is a float between 0 and 1

How is your analog wired back to your PLC? Hopefully you have shielded instrument cable (with screen appropriately terminated) which is run with the maximum possible clearance from noise inducing devices like VSDs and their associated cables.

Filtering in the PLC should be a last resort

HJTRBO said:

I've always liked this format...
FILTERED_SIGNAL = K * ( SIGNAL - FILTERED_SIGNAL ) + FILTERED_SIGNAL
K is a float between 0 and 1

Click to expand...

Thats the basic Low Pass Filter, I may give that a try as well. The larger the value of K, the less filtering effect?

Saffa said:

How is your analog wired back to your PLC? Hopefully you have shielded instrument cable (with screen appropriately terminated) which is run with the maximum possible clearance from noise inducing devices like VSDs and their associated cables.

Filtering in the PLC should be a last resort

Click to expand...

Cabling was already installed & most likely run with noisy cables. Im aware of best practice etc, but this is what they decided to give me...
This used to go a 7-segment display that did used to move, but only by 1-decimal place or so. We moved it to the PLC for indication elsewhere in the plant.

I also have the option of counting pulses, so may give that a try to see how consistent that is.