CompactLogix Analog Card Range Config Via Code

[rtgibson]

I might be missing something simple here but we've set some scaling up on our analogue input cards (4-20mA ranged HighEngineering = 100 LowEngineering = 0 - degrees celsius) Works fine 4 mA gives me 0 and 20 mA gives me 100, everything in between works.

My problem is when I try to change a value via code (for whatever the reason may be config screens etc....) I can see that my new value is moved to the right register and can see it change on the properties of the card config so if I change the the HighEngineering parameter from 100 to 50 I can see the value change but the resultant output value does not change, it ignores the change until the power is cycled... ?

Is there some other command I need to do to change these values while the PLC is running (other than a straight forward MOVE) ?

Thanks Russ

 

[Bit_Bucket_07]

I'm pretty sure that when you change an analog module's configuration while in run mode, you are then asked through a popup dialog box whether you want to update the configuration with the PLC running.

Why would you need to do this anyway? If you want to change the scaling, you could do it with relatively simple logic based upon the numbers that are being returned from the module with the standard scaling that you have already setup.

 

[Contr_Conn]

If you are writing to any configurations tags online, these values will not propagate to the module.
You need to inhibit/uninhibit the module or send Module Reconfigure message.

 

[rtgibson]

What's the module reconfigure message - where's that ?

We are changing values via HMI (so we don't get the chance to OK the configuration popup in Studio5000) - the reason for doing it is just to be able to tweak signals if we get any sensor drift etc. on site. We can and have done it using scaling blocks before - I just wanted to see if I can do it directly via the card parameters (which at first seemed like a better idea).

Thanks for the answers - Russ

 

[rdrast]

IMHO, it is far more flexible (and safer) to just scale the module's channels to something nominal. For 4-20mA, I'd use 4000-20000, and then use a scaling function in logic to convert that to Engineering Units.


Re-configuring a module online should only be done if you are Absolutely Sure everything is correct, and you won't affect other channels, and I just can't see a need for it, ever.

 

[Ken Moore]

The Compacts don't have the same scaling features as the CLX cards. There are 3 or 4 defaults. I usually choose Percent Scale, Then 4=0 and 20= 10000, then scale as needed.

 

[Contr_Conn]

Module Reconfigure is a message type that you can select in dropdown.
It is also in Logic Designer help.