Industrial Engineer · phase 2 of 16
AI / Analog Input
Input that measures a continuous electrical signal such as 4-20 mA, 0-10 V, resistance, or thermocouple voltage.
The Explain card
- Plain English
- An analog input measures a signal that varies smoothly rather than switching on and off. Temperature, pressure, level and speed usually arrive this way.
- Example
- A pressure transmitter sends 4 to 20 mA into an analog channel. The card converts it to a number, and the program scales that number to pounds per square inch.
- Why it matters
- Every analog point needs a range, a wiring type and a scaling before it means anything. A channel configured for voltage while the transmitter sends current reads garbage that looks like a valid value.
- Hook
- Discrete says whether, analog says how much.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
Connect the pressure transmitter to an AI channel, then configure that channel's range and scaling in the PLC program.
Letter by letter
- A Analog also spelled analogue outside customary US engineering usage
- I Input contrasts with the O for Output in AO
Where it came from
- Origin
- an English engineering initialism formed from analog input
- Entered the language
- 1970s
- What changed
- The general electronics phrase became a standard PLC and distributed control system label for a hardware channel or configured point.
How it is spelled
- Capitalisation
- Write AI in uppercase even mid-sentence; write analog input in lowercase unless it appears in a title or label.
- Plural and possessive
- The plural is AIs, though AI channels is often clearer; the possessive is AI's.
- Out loud
- Spelled out letter by letter.
Same family
- AO
- DI
- DO
Broken into chunks
-
analog
- analog signal
- analog output
-
input
- digital input
- input module
Where it sits in the deck
Phase 2: PLC I/O and Field Signals
Where the controller meets the machine: discrete and analog signals, the wiring conventions behind them, and the field devices that send them.
