Industrial Engineer · phase 5 of 16
Explicit Messaging
CIP request-and-response communication used for configuration, diagnostics, and noncyclic data.
The Explain card
- Plain English
- Explicit messaging is a request and a reply. The controller asks a device a specific question, waits for the answer, and the exchange is over.
- Example
- A message instruction reads a drive's fault code, writes a parameter, or fetches a serial number during commissioning. Each one is a single round trip.
- Why it matters
- Explicit messages are the right tool for configuration and diagnostics and the wrong tool for anything the machine depends on every scan. A program that polls a drive with message instructions for its status is slow, fragile and will eventually collide with itself.
- Hook
- Ask a question, get an answer, hang up.
Where it sits in the deck
Phase 5: PLC Industrial Communications
The protocols that let controllers, drives and operator panels talk, plus the addressing and description files that make them agree on what was said.
