System Features; Visible/Audible Devices; Single/Three Button Controls And The Microprocessor - Chamberlain LiftMaster Professional SW420 Installation And Maintenance Instructions Manual

System Features

Visible/Audible Devices

ACTIVITY LED
Steady indication when gate is at either open or close limit.
1 flash per second when gate is off a limit in normal operation.
2 flashes per second when entrapment level one has occurred.
AUDIBLE WARNING DEVICE
If the operator should have a second inherent obstruction in sequence with the first; (i.e. back to
back), the sounder will
prior to gate movement, and stay on during gate movement.

Single/Three Button Controls and the Microprocessor

THREE BUTTON CONTROL (SEQUENCE OF OPERATION)
The three controls on the module are Open, Stop, and Close. The Close control is programmable.
Stop will override all other functions.
If closing, the Open command will cause the operator to stop and
reverse to full open. The Close command will close the gate from
open limit or midstop only.
If SW1 pin 1 is on three button, station will only close the operator
from the open limit or from mid-stop. If SW1 pin 1 is off, the input will
work as a single button (Open, Close, Stop).
SINGLE BUTTON CONTROL (SEQUENCE OF OPERATION)
Open to open limit, close, reopen. If power has been interrupted, the operator will always open
with first activation.
01-G0610F12
Figure 11: SW420 CONTROLLER
activate. Also, the sounder can be programmed to come on 2 seconds
System Features
Figure 12
Doc 01-G0610
Rev A
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