Read/write BOOL data between Logix PLCs

[Sam_R]

Greetings.

I have a 1769-L30ER that runs a new piece of equipment my company bought. I would like to read from and write to some tags on this PLC with a 1756-L82E. I can use a series of MSG instructions to read and write all the REAL and DINT values that I need, but I can't find a good solution for the BOOL data that I need because the MSG instruction doesn't support BOOL data.

Normally I would set up a produce/consume tag structure between two PLCs, but the program on this new equipment is locked and I can't view or edit any existing code.

I thought at first that I would create my own program on this PLC and then pack up all the BOOLs into DINTs for transfer, but most of the BOOLs that I need to see are program-level tags. I can't edit the programs that these tags belong to.

Am I missing an obvious solution, or am I just S.O.L.?

 

[cardosocea]

Create an array of DINT's, transfer the array between PLCs. Map reals, DINTs and BOOLS into the array.



Voila.

 

[Sam_R]

Create an array of DINT's, transfer the array between PLCs. Map reals, DINTs and BOOLS into the array.



Voila.

Is there a way to copy a program-level tag's value without being able to access the logic in that program?

 

[joseph_e2]

I'm not aware of any way to access program-scoped tags from within another program.



Any chance there's a Red Lion HMI on the machine? If so, and if you can edit its program, it's easy to add gateway blocks to transfer data between PLCs.

 

[widelto]

yes, use produced and consumed tags method.

 

[JeremyM]

Is there a way to copy a program-level tag's value without being able to access the logic in that program?

I'm not aware of any way to access program-scoped tags from within another program.



Any chance there's a Red Lion HMI on the machine? If so, and if you can edit its program, it's easy to add gateway blocks to transfer data between PLCs.

Public parameter.

 

[Ken Roach]

Whether intentional or not, a Program-scoped BOOL tag that is in a program you cannot edit is fairly immune to PLC-initiated messaging (onboard or in ar emote PLC) and program logic.

I agree that an HMI or other software that has access to those Program-scope tags might be the best thing to act as a data broker.

If your OEM set up the Program-scope logic to be inaccessible on purpose, they might have also disallowed external access.

 

[GaryS]

I would look at InGear

https://ingeardrivers.com/products/net-products/netlogix/

I beleave they can upload the tag names and types
I know they can read and wright to the tags