We have a system with various brains, controllers, etc.
To set up filtering of analog input channels we have used the “Set Analog Filter Weight” command to specify filter weights for all analog channels at program launch.
This requires us to use PAC Manager to read the scan times in order to come up with an estimate of what filter weights to use to get a filter value near what we want.
Recently, I’ve noticed that some channels, which are on an older style rack, and use a B3000-ENET controller, seem to have much longer filter time constants than what I had expected. And that got me looking into it, so I used PAC-Manager to try to view what the scan times are for this rack, and that data doesn’t appear, probably because the old controller/brain and its old software don’t support that.
On, for example, a rack with an R2 controller, we get these timing values as expected. Here’s what I just read from an R2 in the system, and then the B3000-ENET:
SNAP-PAC-R2
0xFFFF F030 005C 4-Channel Digital Scan Count 826011035
0xFFFF F030 0060 Analog & High Density Dig. Scan Count 1103073955
0xFFFF F030 010C Milliseconds Since Powerup 826671255
0xFFFF F030 0160 Elapsed Time Since Powerup (DD:HH:MM) 158:16:46
0xFFFF F030 0140 Analog & High Density Digital Scanner 13.190 msec/scan
0xFFFF F030 0144 4-Channel Digital Scanner 1.000 msec/scan
SNAP-B3000-ENET-SNMP
0xFFFF F030 005C 4-Channel Digital Scan Count 1391520708
0xFFFF F030 0060 Analog & High Density Dig. Scan Count 361244521
0xFFFF F030 010C Milliseconds Since Powerup 827107196
I thought I might be able to just divide the milliseconds since powerup by the scan counts to arrive at the scan times, but that gives results I find hard to reconcile.
Is there a way to determine the scan time for analog inputs for the analog channels we have installed on the old-style rack with the B3000 controller?
Then, searching to see if this question has been asked before, I ran across a thread about a new running average type command, and in the course of that discussion, it was said that you need to look at the datasheet for a given module, and use its “Data Freshness” value when figuring out what the sample rate would be when setting one of those filters up.
And that got me wondering if all of that will be applicable to us with our old B3000 sections of our system. If those Data Freshness values (and filtering that can use those values) hold true even for the legacy B3000s in our system, that might be a pretty nice way to achieve the desired filtering.
Thanks again, in advance, for any time you spend pondering this for me.