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Rev C Doc 6001242 (01-20273) 31 of 53
4. TANDEM GATE DETAILS
The Tandem gate is typically used in high traffic situations where some control of incoming and/or
outgoing traffic is required. The outside gate is usually a less expensive, fast moving barrier gate (or
light slide gate) which protects the more expensive and less mobile Slide or Swing inside gate. The
outside gate does this by stopping the vehicle until the inside gate is completely open. The Tandem
configuration can consist of any LiftMaster model for Master, and a model SL 1000-B1 (slide gate) or
BG 3000-B1 (barrier gate) for Slave. NOTE: The SW 2000-B1 (swing gate) may not be used for
Slave.
STREET
COMPLEX
Gate
Operator
Master
Gate
Operator
Slave
Exit Loop
Inside Interrupt
Loop
Shadow Loop
(swing gate only)
Outside Interrupt
Loop
Inside Interrupt
Loop
Outside Interrupt
Loop
MASTER
INPUTS:
Radio
Cycle
Interrupt Bar
Fire
MagLock
Manual
Inputs
SLAVE
INPUTS:
Radio
Cycle
Interrupt Bar
Fire
MagLock
Manual
Inputs
SWITCH S1
SETTINGS:
Slide: Unit
Option
Timer: Unit
Option
Retry: Unit
Option
ATG: OFF
Master: ON
Trap: ON
SWITCH S1
SETTINGS:
Slide: Unit
Option
Timer: Unit
Option
Retry: Unit
Option
ATG: Unit
Option
Master: OFF
Trap: OFF
1204F23
Master/
Slave
Cable
: Affects both units.
Figure 19. Typical Tandem Gate Installation.
HOW IT WORKS:
• When a vehicle is entering or exiting
, the inside Master gate opens first. When the Master is
completely open, the outside Slave gate opens, allowing the vehicle to enter or exit.
• The Master unit Reclose Timer (if enabled) does not start counting down until the Slave unit is fully
closed. Since ATG is not allowed in the Master unit, if the Reclose Timer is not enabled, the
Master gate will remain open.
• During high traffic hours, the slower-moving Master gate can be latched open by a continuous
Manual Open input, leaving the faster moving Slave gate to control entering and exiting traffic.
• If a vehicle stalls between the gates and they close, they can be opened by a CYCLE or RADIO
command, or by driving over: the Slave unit Inside Interrupt Loop (SLIDE=ON only), or (optional)
Exit Loop.
• A fault in one unit affects both units (see Troubleshooting/Maintenance for Fault List).