Device Button

Button

This page is generated from the Unity twin. Published from _docs/context/devices/button.md — edit it there, not here. Changes made in the wiki are overwritten on the next sync.

A push button with a lamp in it. One bit up to the PLC saying it is pressed, one bit back down driving its light.

Twin device type · twin FB FB_Button · 2 instances in FG_System · Unity component OC.Interactions.Button

What it is

What an operator actually touches: start, stop, reset, an emergency stop mushroom. The lamp is driven by the PLC, not by the button, so the panel shows what the program believes rather than what the operator just did.

What the PLC sees

Symbol	Meaning
Status.0	Pressed
Control.0	Light the button's lamp

A button takes one bit in each direction. That matters when several are packed into a panel — see PanelSampler.

How the twin models it

Two kinds, set per instance:

Type	What a click does
Momentary	Goes true, and back to false about a tenth of a second later
Latching	Stays true until it is clicked again — the behaviour of an emergency stop mushroom

Buttons appear both as 3D objects in the scene and as controls on the on-screen operator panel; both drive the same bit.

Watch out

A latching button does not release itself. Clicking an emergency stop in the twin leaves the cell in emergency stop until you click it a second time, exactly like twisting the real mushroom back out.

In this machine

Signal — One input and one lamp coil, as a single device. Active while the mushroom is latched.

There are 2 of them, in FG_System:

Device	Twin PLC path	Group
SS_EStop1	MAIN.FG_System.SS_EStop1	FG_System
SS_EStop2	MAIN.FG_System.SS_EStop2	FG_System

Control implementations

The twin is master for structure, and that is all this page states. Which control function block each instance becomes, its process-image members and its published HMI struct is the control platform's own knowledge base:

• Beckhoff
• Siemens — no knowledge base published yet