RsLogix 5000

HI,
I am having a problem understanding the differences in the tag types( Base, Alias, Produced and Consumed) and when they are used, needed or best one to chose out of for RsLogix 5000. Thank you all for your help in advance.
Sincerely:
Jeff

Greetings Jeff ...

let's say that a baby boy is born ... the name on his birth certificate is filled out:

Clayton Runnymede Endicott, III ...

his father takes one look at the little guy and says "I'm going to call him Peewee" ...

now suppose that a bit (that's a box that can hold a one or a zero) is created inside a PLC's memory ... the name on the box (its "tagname") happens to be:

Local:3:I.Data.4 ...

that's like the official name on the birth certificate ... it nails down the precise address of the bit (the box) and the terminal screw that's assigned to that bit/box ... this is the BASE tagname that you asked about ...

now suppose that the PLC programmer gets tired of saying the whole long drawn-out official name "Local:3:I.Data.4" every time he wants to use that bit/box or its terminal screw ... so he assigns a "nickname" (like Peewee) to the bit/box ... maybe "Start_Button" would make sense ... this is the ALIAS tagname that you asked about ... (think "handy nickname" and you've pretty much got the idea) ...

as for a "Produced" tagname think "Transmitted" or "Out-going" ... (there's more to it than this – but we're trying to keep things simple) ... the main idea is that a "Produced" tagname is set up (created) to be automatically "transmitted/sent" from one device/processor/controller to another device/processor/controller ... so that the second device can KNOW what the first device is up to ... ("I'm starting my end of the machine – so you start yours too") ... (think about an "OUT" mail basket on an office desk and you'll be pretty darn close) ...

as for a "Consumed" tagname think "Received" or "In-coming" ... (again, there's more to it than this – but blah-blah-blah) ... the main idea is that a "Consumed" tagname is set up (created) to be automatically "received" from one device/processor/controller by another device/processor/controller ... in simplest terms, it's just the other end of the "produced/transmitted" operation that we talked about above ... (an "IN" mail basket on an office desk should give you the main idea) ...

so ... summing up ...

can you live with clunky names like Local:3:I.Data.4 without any heartburn? ... if so, just stay with the BASE (official birth certificate) tagnames ...

want something easier to remember? ... assign a meaningful ALIAS tagname that makes more sense to you ... ("Start_Button" for example) ...

got some information to send from one device/processor/controller to another? ... set the tagname up as PRODUCED ...

now then ... you'll need a place inside the receiving device/processor/controller to land that piece of incoming information ... in this case, a CONSUMED tagname is the usual way to go ...

finally ... when you set up your very own internal tagnames (something along the lines of B3/0 in an SLC) then the name that you pick out is going to be a BASE (birth certificate type) tagname ... example: "My_Name_For_The_Timer" ... (reason: it doesn't have any other name to identify it - so this is the BASE) ... anyway, just suit yourself and pick something that makes sense to you ... now you COULD also make up and assign an ALIAS (nickname) for it if you wanted to – but would that make things easier – or more complicated? ... it's up to you to decide ...

I hope this helps ...

Bravo once again!

I like the nickname comparison.

There's another way to think about and use an alias. For us this is in terms of a Panelview Plus display. When the display asks for the status of a ControlLogix variable it asks for it by name. So for Local:3:I.Data.4 (from Ron's example) the display would ask for that name specifically (not some numeric memory location). Well the structure of some of our controls means that always present inputs and outputs may have to be run to different I/O points on different machines. What we do is alias the actual function names to the appropriate iput or output "Local...." points. The display is set up to ask for the alias name. So we don't have to change the display for each I/O revision.

To emulate Ron's type of analogy - the president of the company knows there's a janitor but the person filling that role changes often. Instead of trying to memorise the often changing name of the janitor the president just asks for "the janitor". "The Janitor" is the alias for whoever is performing that function.

Thank You

Thank you so very much for the explanations. It helped to make it crystal clear in my understanding. I appreciate you all taking time to help. Hope everyone has a great day.
Sincerely:
Jeff