Big plants run many Logix controllers that must swap data. Logix gives you two tools: Produced/Consumed tags — a producer publishes a tag and consumers see it update automatically every cycle — and the MSG instruction — a one-shot read or write you trigger on demand. Push data continuously, or fetch it when you ask. Try both.
Controller A (the line master) produces LineSpeed; Controller B consumes it. Change A's value and — in Produced/Consumed mode — B mirrors it automatically each cycle, no code on either side beyond the tag config. Switch to MSG mode and B only updates when you fire a message: explicit, triggered, one packet at a time.
In Produced/Consumed mode, B is always in step — A's change flows over the connection at the configured RPI. In MSG mode B holds the old value until you fire a message: see the gap open when you bump A without sending. Produced/consumed for fast, repetitive sharing; MSG for occasional, on-demand transfers.
📤📥 Produced/Consumed — a standing connection that pushes a tag every RPI. Deterministic, low-overhead, ideal for data many controllers need continuously (line speed, e-stop status). Costs a connection on each side.
✉️ MSG instruction — a triggered, one-shot read/write (CIP). No standing connection; you control exactly when. Great for recipes, occasional commands, or reaching a device you rarely talk to. Watch the .EN/.DN/.ER bits.
Both ride CIP over EtherNet/IP (next track). Produced/consumed is "implicit" cyclic messaging; MSG is "explicit" on-demand messaging — the same two flavours you'll meet again when you add I/O.
Twelve controllers all need the master's live line-speed, updated continuously with minimal code. What do you use?