1769-HSC Active Ranges

PLC Pie Guy

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Join Date
Jun 2013
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Halifax
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Hey All.

I'm using a 1769-HSC on a version 21 controller.
My goal is to use the active range outputs to control line peripherals.
It works great. Great until I want to change the limit values. I can move a new value for example into the tag "Local:X:C.RangeActive0To11[0].LowLimit". The card configuration will even show that the value is there, but the active range doesn't respond to the change until a power cycle or a download.

So I asked Rockwell.

Long answer short, the values of ranges 0 to 11 cannot be changed on the fly. Values 12 to 15 CAN be changed with a Load Direct Write instruction.
As well as they gave me a technote that says I must inhibit the module and...

"To programmatically inhibit a module, an SSV instruction must be used"
Technote 52041.

They say to inhibit the module, then uninhibit the module. My question is.....


Is this how you folks do it to make constructive use of the active ranges??? I mean, to inhibit the module while a machine is running seems risky, won't I miss counts while the module is inhibited??

How would you best make use of the Actual position to fire peripherals at a given position. Simply using an EQU or GEQ OR a LIM instruction just seems so unpercision to me when I have the active ranges available.

Advice or criticism is welcome.

Thanks a bunch!

P.S. It snowed here yesterday on October 18, CRAZY!
 
I do LIM instructions and use the HSC in a ring configuration since I never had good look toggling the inhibit of the module. And you're right - while it's inhibited it doesn't function so if you have multiple processes at once you're screwed.

How accurate do you need to be? The LIM will obviously depends on scan time, but I've never had an issue in regards to that.
 
I'm not using it as a ring counter. I'm using a reset prox. This encoder is on a production line. Its not quite a perfect 3:1 line position to encoder rotation. I reset the count with the prox roughly 3 times a revolution with the Z input. (Hats off to folks here for helping with that!) Then measure distance in pulses. At a given distance I fire an output. Over and over and over and over.... It happens fast (120/min, fast for a fillers standard) so accuracy is my goal.
I have been doing this with the LIM instruction on an Ethernet encoder. It was to slow so I switched to this HSC set up and a traditional 1024 encoder. Its much better now but i'm still using the LIM instruction to fire the outputs. I thought it would be so much cleaner to use the active ranges and in my puny mind I'm thinking this happening in the card and turning on an active range bit would be faster than evaluating the current count for a value equal to my set point then turning on a bit.
Perhaps I will just continue with the examining of the current count.

Thanks
 

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