Add On Instruction help AOI

GTUnit · Apr 9, 2012

Hello,
I am working on projects where the individual alarms number in the hundreds.
I am trying to creat a Add On Instructions which allows me a simple way of consolidating the individual alarms into a main "System Alarm" and a main "System Shutdown" tag.

Does anyone have any input on a good way to do this?

Some of my sensor AOI look like this: (attached pic)

I just enter the sensor name in the AOI and it creates all the necessary tags for the sensor.

Now I need to enter a few hundred sensor names into something and have it spit out "shutdown" tripped and "alarm" tripped.

Is there a way to do this without writing it out in ladder?

Kev77 · Apr 9, 2012

What are the conditions that will trigger alarm or shutdown? Could you make an AOI for each input module. This will help with single ended analog. If you are just looking for something to generate tags then wouldn't UDT's do the trick? Add-on instructions help when you need to process the same logic with different tags.

rdrast · Apr 10, 2012

A quick question ... Why not just use the ALMA instruction for analogs like that?
Using any complex alarm block though is going to require to to do some more legwork somewhere in the program to AND/OR the results together to an overall status bit/word.

For most of that background work, I actually prefer to just use a structured text routine to do the overall summations.

The Plc Kid · Apr 10, 2012

rdrast said:
For most of that background work, I actually prefer to just use a structured text routine to do the overall summations.

Just curious what is the advantage of doing it in ST over ladder or function block?

GTUnit · Apr 10, 2012

Kev77 said:
What are the conditions that will trigger alarm or shutdown? Could you make an AOI for each input module. This will help with single ended analog. If you are just looking for something to generate tags then wouldn't UDT's do the trick? Add-on instructions help when you need to process the same logic with different tags.

The conditions are not too relevant and are handled in the AOI that I created for each input module. Im really trying to OR a ton of tags together efficiently.

GTUnit · Apr 10, 2012

rdrast said:
A quick question ... Why not just use the ALMA instruction for analogs like that?

We created our own Alarm AOI for 2 reasons:
--Practice for someone like myself who has not used them before.
--Better suited to our needs since it Scales Raw Input, Has Individual Alarm Filters, combines Alarms with Shutdowns

rdrast said:
Using any complex alarm block though is going to require to to do some more legwork somewhere in the program to AND/OR the results together to an overall status bit/word.

For most of that background work, I actually prefer to just use a structured text routine to do the overall summations.

I should have mentioned that my programming skills are on the very low intermediate to high beginner level.

We literally have hundreds of alarms in some of these projects and I was hoping to create a scalable system which would allow us to enter/handle these alarms in an efficient manner.

I have not written in structured text before but I will learn if you recommend that approach.

Darkzadow · Apr 10, 2012

I am new to PLC programming so balls to my knowledge, but could you have an array of referenced inputs and write the AOI to parse through the array and keep a running total of alarms?

rdrast · Apr 11, 2012

The Plc Kid said:
Just curious what is the advantage of doing it in ST over ladder or function block?

A couple reasons, it is more concise, so you can see more on a page, I can use my favorite programming editor, and I'm much faster typing then icon dragging and mousing around.

For things like simple summations or just moves that really never need to be edited it is much cleaner just to keep them out of the way of actual control logic (IMHO).

Example:

// Alarm summation and enable:



Result_Bool := 

 (

   Bool_Tag_1 OR 

   Bool_Tag_2 OR 

   Bool_Tag_3 OR

   Bool_Tag_4 OR

   Bool_Tag_5 OR

   Bool_Tag_6 

 ) 

 AND

 Summary_Enable;



 // HMI Moves :



 HMI_Tag_1 := PLC_Speed;

 HMI_Tag_2 := PLC_Load;

 HMI_Tag_3 := PLC_Reference;

MichaelG · Apr 11, 2012

Where ever possible I use ladder - especially in AOI that are called often
Reason is execution time

Try a test call the same AOI 1000 times in a in loop
Then Call a Ladder AOI 1000 doing the same
the Ladder will be faster

I have been caught out with ST in a AOI before and had to re-write in ladder

shooter · Apr 11, 2012

in your ladder say in every block OR the alarm and the alarm of the previous one.
alarm= alarm or rungalarm in every set.
When any alarm exists the alarm output wil be true.

The Plc Kid · Apr 11, 2012

rdrast said:
I can use my favorite programming editor

Which editor do you use for this?

Add On Instruction help AOI

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