Monday, March 29, 2010

Harder Working CHARMs

I’ve got my beta copy of DeltaV version 11 and so of course, I’m looking for all the cool things that didn’t get mentioned at Emerson Exchange in Orlando. But first, a little disclaimer – I’m working with beta software, so YMMV!

First up is the Signal Characterization tab of a DI CHARM. The tab magically appears when you select a CHARM class of Discrete Input. 

While the De-Bounce Filter caught my eye, it’s the Output Filter that holds some interesting promise for new, innovative control applications. A quick look at the Help associated with the dropdown reveals:
The Extend sounds like a timed pulse – when the input triggers, the output (what your DI or DC function block would see) latches in for a configured amount of time, regardless of how the input changes.

The Delays sound like they’ll take care of chattering inputs – stay tuned for an explanation of the Delay versus the Delay On/Off. Looks like BOL needs an update.

Edge triggering at the CHARM? I’ve already started dreaming and scheming how to exploit this new feature.


Erin and Aaron said...

So is this done in the CHARM or in the controller?

Bruce Greenwald said...

Since the choices for time duration can be as fast as 50 ms, I'm thinking this is done at the CHARM.

Erin and Aaron said...

Wow. That seems like a pretty big deal. Maybe not, though - I take it it was doing something similar already in the traditional IO card?

alarmist said...

Bruce: Can you recommend conditions or guidelines on when to use on-delays and when off-delays are a better option? Is 'Settle' a good handle to 'delay' alarms at plant startup?

Bruce Greenwald said...

Now that we have our real CHARMS and the production release of 11.3, we're going to be doing some extensive testing - expect a new blog post and YouTube video within the week.