# Select-before-operate command interface

Canonical URL: https://eloragrid.ai/symbols/select-before-operate-command-interface
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: SCI
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: substations
Input: Selection and operate requests
Output: Selected equipment command

Separates equipment selection from the subsequent operating request in the selected control scheme.

## In plain English

### What this block does

Separates equipment selection from the subsequent operating request in the selected control scheme.

### A simple example

In a substation control building, the station controller receives bay information and forwards an operator's selected command to the correct bay device. Device feedback confirms whether the intended result actually occurred. For this reference, the drawing identifies “Selection and operate requests” at the input and “Selected equipment command” at the output. The exact control model is device-specific.

### What the drawings help you do

Start at the named input: Selection and operate requests. Identify its source device or document and the state represented on the drawing. Follow the named output: Selected equipment command. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Selection and operate requests
- Output: Selected equipment command
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Selection and operate requests → SCI → Selected equipment command
A reading guide. The entry's original illustration and input/output facts describe this application.

- [SEL-2411 programmable automation controller](https://selinc.com/products/2411/)


## What it represents

Separates equipment selection from the subsequent operating request in the selected control scheme. Station automation collects measurements and statuses and issues assigned commands through defined authority paths. A communicated point has a value, quality and equipment identity; it should not be treated as an unexplained contact.
In a substation control building, the station controller receives bay information and forwards an operator's selected command to the correct bay device. Device feedback confirms whether the intended result actually occurred. For this reference, the drawing identifies “Selection and operate requests” at the input and “Selected equipment command” at the output. The exact control model is device-specific.
Document the point mapping, source, destination, command authority and failure behavior. A communication interface block explains information flow and does not certify network security or control-system availability. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.

## How to read it

- Start at the named input: Selection and operate requests. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Selected equipment command. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- The exact control model is device-specific.
- Document the point mapping, source, destination, command authority and failure behavior. A communication interface block explains information flow and does not certify network security or control-system availability.

## Information to show or reference

- Label the source and connection reference for selection and operate requests.
- Identify the destination and defined state of selected equipment command.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: The exact control model is device-specific.

## Important distinction

The exact control model is device-specific. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.

## Facts

- Representation: Functional block
- Installation focus: Substations
- Input / boundary: Selection and operate requests
- Output / connection: Selected equipment command
- Lookup label: SCI is a library lookup label, not a standard device designation.

## Public references

- [SEL-2411 programmable automation controller](https://selinc.com/products/2411/) — SEL. Public technical context for substation automation and command interfaces. Station I/O, alarms, event recording, command and communications interfaces. The application text and educational graphic are independently authored; the publisher does not certify this representation.

## 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.