The RDR2SA is a Remote Dual Relay/Two-Channel Supervised Auxiliary Module for Johnson Controls (formerly Simplex/Grinnell) TrueAlert and TrueAlarm emergency communications and fire alarm systems. It is part of the Simplex 4000/4100U and 4010/4020 legacy product families.
Its primary function is to provide two remotely located, configurable Form-C relays and two supervised input circuits for monitoring auxiliary devices, all while communicating on a single addressable loop.
Key Functions and Features
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Dual Configurable Relays:
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Provides two physically separate Form-C relay outputs (SPDT – Single Pole, Double Throw).
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Each relay can be independently programmed via the system software for various functions, such as:
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Alarm Control: Activating horns, strobes, or other notification appliances in a specific zone.
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Equipment Control: Shutting down HVAC, closing fire doors, controlling dampers, or releasing magnetic door holders.
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Supervisory or Trouble Signals: Indicating conditions like sprinkler valve closure.
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Two Supervised Input Circuits (Auxiliary Monitor Points):
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Each input circuit can monitor a normally open (N.O.) or normally closed (N.C.) dry contact from an external device.
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Used to monitor the status of devices not on the addressable loop, such as:
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Waterflow switches and valve tampers (supervisory signals).
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Conventional smoke or heat detectors (alarm signals).
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Manual pull stations.
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Guard tour stations.
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Addressable Loop Device:
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Connects directly to the SLC (Signaling Line Circuit) loop of a compatible Johnson Controls/Simplex fire alarm control panel (FACP).
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Occupies two consecutive addresses on the loop (one for the relays, one for the inputs).
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Communicates status (Normal, Active, Trouble) back to the main control panel.
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Supervision and Style Options:
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The input circuits and wiring are supervised, meaning the panel can detect open circuits, short circuits, and wiring faults.
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Can be wired in Style Y (Class B) or Style Z (Class A) configurations for high reliability.
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Typical Applications
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Expanding System Outputs: Adding relay control points where needed without running individual wires back to the main panel.
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Integrating Non-Addressable Devices: Bringing the status of conventional devices (like waterflow switches) onto the intelligent addressable loop.
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Notification Appliance Circuits (NAC) Control: Remotely powering and controlling horns, strobes, or speakers in a specific area.
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Building System Interface: Providing a reliable fire alarm interface to control HVAC, elevator capture, door release, or other life-safety functions.
Technical Specifications
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Model: RDR2SA (S300-D1N-RDR2SA)
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Catalog Number: 24-10239-472
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Compatibility: Simplex 4000/4100U, 4010/4020, and other legacy Simplex panels using the same protocol.
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Loop Voltage: Operates on the SLC loop voltage provided by the panel.
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Relay Contacts: Form-C, rated for 2.0 amps @ 30VDC resistive.
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Inputs: Two supervised, configurable for N.O. or N.C. dry contacts.
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LED Indicators: Power, Active, and Trouble LEDs for status indication.
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Wiring: Terminals for SLC In/Out, Relay outputs, and Input circuits.
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Mounting: Typically mounts in an electrical enclosure or directly to a 4-gang electrical box backplate.













