Industrial Engineer · phase 5 of 16 · noun
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.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
During commissioning, a Logix controller uses Explicit Messaging to read parameter 1 from a PowerFlex 525 drive over EtherNet/IP.
Why these words
- explicit Latin explicitus, unfolded or made clear modifies messaging to indicate that the communication is directly specified
- messaging message plus the English suffix -ing names the activity of exchanging messages
Where it came from
- Origin
- English technical compound; explicit comes from Latin explicitus, while message came through Old French from Latin missus, sent
- Entered the language
- 1990s
- What changed
- Explicit moved from the sense of unfolded to clearly stated, and messaging developed from carrying a message to exchanging information electronically.
How it is spelled
- Pattern
- explicit keeps the Latin-derived letter sequence -plicit
- Pattern
- messaging drops the final silent e of message before -ing
Spelled like
- implicit
- complicit
- staging
- raging
Broken into chunks
-
ex-plicit
- implicit
- complicit
-
message
- messenger
- messaged
-
-ing
- wiring
- programming
What it sits beside
Same subject
- CIP
- MSG instruction
- EtherNet/IP
- parameter object
Same shape
- explicit instruction
- explicit conversion
- explicit addressing
CIP communication types
- explicit messaging
- implicit messaging
CIP attribute services
- Get Attribute Single
- Set Attribute Single
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.
