# IEC priority encoder (HPRI/BIN)

Canonical URL: https://eloragrid.ai/symbols/iec-priority-encoder
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: HPRI/BIN
Drawing use: Schematic
Reference families: IEC, Manufacturer

## Symbol convention

Convention: IEC
Form: X/Y coder with HPRI/BIN qualifier
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Related representation: [Priority encoder](https://eloragrid.ai/symbols/priority-encoder)

IEC coder marked HPRI/BIN that outputs the binary number of the highest-priority active input.

## In plain English

### What does IEC priority encoder (HPRI/BIN) mean?

A priority encoder is shown as an X/Y coder with the additional drawing mark HPRI/BIN: highest priority in, binary out. Inputs are numbered by priority, and outputs carry binary weights. Additional outputs often signal that any input is active, which lets stages be cascaded.

### A simple example

On control drawings priority encoders reduce many alarm or request lines to a code, for example to identify the most important active fault for display. The input numbering must match the intended priority order.

### What the drawings help you do

The symbol does not state whether inputs are latched. If the encoder input is a momentary event, a latch stage is needed before it.

### This particular reference

IEC coder marked HPRI/BIN that outputs the binary number of the highest-priority active input. A plain binary encoder assumes only one input active; HPRI resolves multiple active inputs.

### Terms

- Signal: Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf)
- [SN74HC148 — priority encoding](https://www.ti.com/lit/ds/symlink/sn74hc148.pdf)


## What it represents

A priority encoder is shown as an X/Y coder with the qualifier HPRI/BIN: highest priority in, binary out. Inputs are numbered by priority, and outputs carry binary weights. Additional outputs often signal that any input is active, which lets stages be cascaded.
On control drawings priority encoders reduce many alarm or request lines to a code, for example to identify the most important active fault for display. The input numbering must match the intended priority order.
The symbol does not state whether inputs are latched. If the encoder input is a momentary event, a latch stage is needed before it.

## How to read it

- Higher input number normally means higher priority.
- Look for group-select or any-active outputs used to cascade.

## Information to show or reference

- Number inputs in priority order.
- Show output weights.
- Show cascade connections.

## Important distinction

A plain binary encoder assumes only one input active; HPRI resolves multiple active inputs.

## Facts

- Qualifier: HPRI/BIN
- Function: Encodes highest-priority active input
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)](https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf) — Texas Instruments. Coder qualifiers, including code designations.
- [SN74HC148 — priority encoding](https://www.ti.com/lit/ds/symlink/sn74hc148.pdf) — Texas Instruments. Priority encoder documentation.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.