Industrial Engineer · phase 5 of 16 · noun

Implicit Messaging

CIP communication used for time-critical cyclic I/O data through an established connection.

The Explain card

Plain English
Implicit messaging is the scheduled, cyclic traffic that carries I/O data over CIP. The connection is set up once and then data flows at a fixed interval without anyone asking for it.
Example
An input block sends its sixteen bits to the controller every 10 milliseconds, and the controller sends its outputs back on the same schedule. Nobody in the program writes a read instruction.
Why it matters
This is the traffic that runs the machine, and it has a timeout, so a few missed packets put the device into its fault state. It is also UDP, which is fast and unacknowledged, so a noisy switch shows up as connection faults before it shows up anywhere else.
Hook
The data that arrives whether you ask or not.

Word knowledge

How the word is built, where it came from, and what it sits beside in memory.

In a sentence

The ControlLogix controller uses Implicit Messaging to update the PowerFlex 525 speed reference and receive its status word at each requested packet interval.

Why these words
  • implicit Latin implicitus, entangled or involved modifies messaging to indicate that the exchange follows arrangements already contained in the connection
  • messaging message plus the noun-forming suffix -ing names the activity of passing messages between devices
Where it came from
Origin
English technical compound formed from implicit and messaging in Common Industrial Protocol terminology
Entered the language
1990s
What changed
Implicit developed from the sense of something enfolded or involved into something understood without separate expression, while messaging developed from carrying a message into electronic data exchange.
How it is spelled
Pattern
The prefix in- becomes im- before p in implicit.
Pattern
Message drops its final silent e before the suffix -ing.

Spelled like

  • imply
  • impossible
  • managing
  • damaging
Broken into chunks
  • im
    • imply
    • implant
  • plic
    • explicit
    • complicate
    • replicate
  • message
    • messages
    • messaged
  • ing
    • polling
    • scanning
What it sits beside

Same subject

Same shape

CIP message types

connection timing terms

  • requested packet interval
  • connection timeout multiplier

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.

Neighbours in this phase