Set Coil

The Set Coil is a ladder-logic instruction that turns ON the bit memory addresses associated with it when the rung status is true. The bit memory stays ON after the rung goes false, so it must be turned OFF by a Reset Coil elsewhere in the program. A single Set Coil can turn ON more than one bit memory address at the same time by giving a start and end address.

Source checked9/9 values · 2026-10-26

Specification

1 source

Language	ladder
Code	Set
Syntax	Set Coil (Bit Memory Address1, Bit Memory Address2 optional, Immediate optional for Y)

Parameters

Name	Description
Bit Memory Address1	Bit memory address associated with the Set instruction; typed directly in the address field or chosen with the Browse Button.
Bit Memory Address2	Optional bit memory address identifying the end of a consecutive range of bit memory addresses to be set simultaneously; leave blank to set only one address.
Immediate	Turns on the output(s) immediately; available only for actual Y outputs and grayed out until a Y address is chosen.

Study notes

The instruction latches: the addressed bit memory remains ON after the rung becomes false.
Bit Memory Address1 sets the first address; the optional Bit Memory Address2 marks the end of a consecutive range of bit memory addresses set simultaneously.
Leave Bit Memory Address2 blank to set only one bit memory address.
The Immediate option is only available for actual Y outputs and is grayed out until a Y address is chosen.
When Immediate is selected, an Immediate Icon appears next to the Set Coil in the Ladder Editor.
Each Set Coil in a ladder program should be accompanied by a Reset Coil to turn OFF the addresses it turned ON.
In Example Program 1, X001 turning ON sets Y001, which stays ON after X001 turns OFF.
In Example Program 2 (Immediate, Y memory only), X001 turning ON immediately sets both output status bit Y001 and the physical output point, Y001 being the 1st output point on the CPU module.