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pmcmahill

DH+ with ControlLogix Master / PLC 5 Slave

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I am relatively new to ControlLogix and have never done DH+ communication. I think I have figured out SLC to SLC, But I am having trouble with a ControlLogix Master and a PLC5 Slave. I have a good DH+ signal and am able to go online with the PLC5 via the DH+ link. What I am not sure of is how to set up the read - write messages in the Control Logix so that data is shared between the two. Any help would be appreciated!

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I see no one's jumped on this so I'll take a stab. I must warn you that my controllogix experience is limited, but I just loaded version 13 on my PC so maybe I can help. DH+ is a peer to peer protocol, not master/slave. Each station gets a turn with a token passing scheme. Anyway, you could choose to read and/or write the data from either PLC. I would put both the reading and writing in one PLC (the controllogix processor) if possible. The MSG instruction is what you want to use for both reads and writes. To configure the MSG instruction, go to your RSLogix5000 help index tab and type "specifying PLC-5 messages". All the details are there to help you determine what type of message and tags you should use for each type of PLC data. Since you already have a communication path, I think you can browse to the PLC5 processor on the Communication tab. The MSG instruction requires a control tag of the MESSAGE type. When you enter the MSG instruction, enter an existing MESSAGE type tag or type a new tag name and it will default to the correct type when you right click and create the new tag. Hope this helps.

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Thanks ... that was helpful When I said Master / Slave, I was refering to the fact that the Control Logix was going to be doing the reading and the writing while the PLC5 was not going to have the read / write logic. Thanks for the info! Pat

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