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Newbie Tony

PLC5 to PLC5 comm (MSG)

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I have two PLC5s connected via DH+. I want send PLC5 (A) the following info: N171:1/6, N172:1/6, N173:1/6, N174:1/6, N175:1/6 & N176:1/6. How do I setup the MSG in sending PLC and receiving PLC?

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You only have to have an MSG command on one side. I would put it in the receiving PLC5, and use a PLC5 Typed Read messaging type. I haven't done that exact type of message, so I would have to search on AB's knowledgebase for the exact setup.

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I'm intrigued! And anxious to learn how to format the MSG message so it can receive the PLC5 A's info (listed above).

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Do you have access to the knowledgebase? Some of it is free, and some requires a support contract. The hardest part of messaging is figuring out the communications path.

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The manual is the best place to start, see pdf below. The addresses you posted are bit addresses, you can only message whole words. So you will have to send or receive all four words and then pick out the bit address you need. You might consider " Global Status Flags" check your manual for more info on this. Message.pdf Edited by Mickey

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I do and have a support contract. Can you provide a link?

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http://www.rockwellautomation.com/support/ is the beginning of all support resources, including the literature library and the Knowledgebase. PLC-5 to PLC-5 messaging is pretty straightforward. Highlight the MSG instruction and press F1 to launch the Help file in RSLogix 5, or read the Instruction Set Reference. You designate the PLC-5 memory addresses you want as the source data (in the remote PLC) and the PLC-5 memory addresses you want as the destination (in the local PLC), and how many you want to transfer. MSG instructions use a Control block, so you'll have to configure one of those. MSG instructions execute on a false-to-true transition of the rung, so put a timer or other periodic logic in your program to trigger the MSG instruction. Unfortunately the addresses you cited are all in different Data Files, so they cannot be read with a single MSG instruction. If I were you I would consolidate that data into bits in a single Word, or a small block or Words, and use the MSG instruction to transfer that.

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