A little "BIT" confused! please L@@k

gr8benwa

Member
Join Date
Mar 2012
Location
indiana
Posts
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Hi guys, this should be extremely easy for someone to answer but I am practicing writing my first Rslogix 5000 program. I am very familiar with Rslogix 500. I have not figured out how to write a bit such as B3:0/0 in 500 into 5000.



500
I:2.0/0_____________________B3:0/0
----] [----------------------( )----

B3:0/0______________________O:1.0/0
----] [----------------------( )----

now using the above, how do I address a OTE bit and XIC in 5000?


5000
Local:2:I.Data.0_____________??????
----] [----------------------( )----

??????______________________Local:1:O.Data.0
----] [----------------------( )----



Another question that would help me with some plc lingo....
What is the proper term for a "bit" such as B3:0/0 that is linked to a virtual address unlike a O:1.0/0 which reflects a real world discrete contact? I'm just use to rslogix 500 calling a B3:x/x type instruction a bit so I dont know how to find it in 5000
 
Many users call them "bits", but they're really "Boolean Data Type Tags".

In RSLogix 500, you addressed individual bits inside 16-bit data words in the B-type or N-type data tables.

Is RSLogix 5000, "bits" can have their own "atomic" datatype. They aren't necessarily part of a larger data element.

You can address the "bits" that are part of a larger data type, like a SINT, INT, or DINT. But you can also create and reference standalone BOOL type tags.

In the above example, you would make a BOOL tag named "FOO":


Local:2:I.Data.0                FOO
-------] [----------------------( )----

FOO Local:1:O.Data.0
----] [-------------------------( )------



Since you're learning RSLogix 5000 for the first time, you'll also want to read up on the technique of "Alias" tags.

Adapting to the tag-based memory structure in RSLogix 5000 is a big challenge, even for experienced users. For a solid year in the late 1990's I was firmly against this newfangled, inefficient, long-winded addressing mechanism. Now I trip over myself every time I have to use a MicroLogix and remember to be efficient in laying out my data tables.
 
right-click on the question mark where the address goes ... click New Tag from the menu ... type in a name (example: B3_0) ... note that you can't use the colon or slashes that you're used to ... say ok ... you've got yourself a bit (or BOOL) ...

technically, a meaningful name like Grinding_Cycle_In_Progress would be better than B3_0 - but let's keep it simple to begin with ...

you won't have any addresses (or "tags" as they're called nowadays) for real-world input or output devices (switches, lamps, etc.) until you add the modules for the inputs and outputs to the I/O List at the bottom of the Project Tree ...

once you've added the modules, you can double-click on the question mark where an address goes - then click the pull-down button - and (as we say in the boot camp) "follow your heart" ... when you see a plus sign, click it ... it means "I've got more to show you" ... the real-world devices will have tagnames like: Local:1:I.Data.0 ...
 
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