Chamberlain LiftMaster Professional SW420 Owner's Manual page 26

PROGRAM SETTINGS (DIP SWITCH S2)
EDGE/PHOTO OPEN
This switch (S2-3) selects edge or photo sensor for the gate
opening protection input.
Open Photo Eye (Pause): When the controller is configured
for photo eyes, the input functions to pause the gate during
the opening cycle. Once the input is cleared the gate
continues to open.
Open Edge: When the controller is configured for safety
edges, the input functions to reverse the gate to the close
limit when the edge is activated during the opening cycle.
S2
ON
ON
1 2 3 4
MASTER/SECOND SYSTEMS
Dual Gate Communications
The control board is capable of running the operator in a master
or second mode depending on (S4) switch setting.
Before initiating any command the master unit queries for the
presence of a "second unit" for a time period of one second. If
the master gets no response the operator will operate in a stand
alone mode. NOTE: For single unit applications, a jumper must be
placed between 11 and 12 of the field wiring terminal block. In
this mode no further communications will take place during
travel. If the master detects the presence of a second unit the
master will continue to query the second unit during travel. The
second unit will send a response to the master for every query.
The second operator will stop if there is a period of one second
or more of no communications.
TRAFFIC
SAMS
Conduit
S2
ON
ON
1 2 3 4
STREET
Second
EDGE/PHOTO CLOSE
This switch (S2-4) selects edge or photo sensor for the gate
closing protection input.
Close Photo Eye (Reverse): When the controller is
configured for photo eyes, the input functions to reverse the
gate to the open limit when activated during the close cycle.
NOTE: Timer-to-Close will reset if enabled.
Close Edge: When the controller is configured for safety
edges, the input functions to reverse the gate to the open
limit when activated during the close cycle. The entrapment
is not cleared at the limit and the Timer-to-Close will be
disabled. The Timer-to-Close may be enabled by activating
the interrupt loop, soft open or hard open input.
S2
ON
ON
1 2 3
When two operators are connected in dual gate configuration
accessories may be connected to either the master or second.
NOTE: Do not run Master/Second communication wiring in the
same conduit as the power and control wiring. The Second unit
will require a normally close stop circuit for proper system
operation. After Master/Second wiring has been completed and
the S4 switch programmed, both units must have their power
cycled to initiate proper Master/Second communication. The
motor learn function must be completed in stand alone mode
prior to Master/Second wiring.
Master or Standalone
Gate Setting
Master
Unit
ON
S4
Second
Unit
Terminal
Block
Shielded Cable
minimum 18 gauge
COMPLEX
OR
PARKING LOT
26
S2
ON
ON
4 1 2 3
Second Gate
Setting
Master
Unit
ON
S4
Second
Unit
Terminal
Earth Ground Rod
Block
(One Side Only)
(twisted pair)
Conduit
4