Description
The Edwards 3-RS485B is a network communications card designed for EST3 fire alarm and emergency communication systems. It provides Class A or Class B circuits for network communications and an additional Class B circuit for digitized audio signals. The 3-RS485B mounts directly to the 3-CPU1 and retransmits network messages to extend wire run distances and ensure reliable inter-panel communication.
Technical Specifications
| Condition |
New/Never Used Surplus |
| Brand |
Edwards |
| Category |
Computer |
| Part Number |
3-RS485B |
| Subcategory |
Communication Card |
| Mounting |
Directly on 3-CPU1 |
| Voltage |
24 VDC |
| Current (Standby) |
98 mA |
| Current (Alarm) |
98 mA |
| Network Configuration |
Class A (Style 6) or Class B (Style 4) |
| Audio Configuration |
Class B (Style 4) |
| Isolation (Network) |
Port A not isolated, Port B isolated |
| Isolation (Audio) |
AIN/A BIN isolated, AOUT/BOUT not isolated |
| Maximum Wire Size |
18 AWG (0.75 mm²) minimum twisted pair |
| Maximum Circuit Length |
5,000 ft (1,524 m) between any three panels |
| Circuit Resistance |
90 Ω maximum |
| Circuit Capacitance |
0.3 µF max (network), 0.09 µF max (audio) |
| Nodes Supported |
Up to 64 panels |
| Media Options |
Copper or fiber with 3-FIBMB |
| Operating Temperature |
32°F to 120°F (0°C to 49°C) |
| Humidity |
0–93% non-condensing |
| Application |
Network and audio communication in EST3 systems |
| Weight |
0.25 lbs |
Information About 3-RS485B
The 3-RS485B is part of the Edwards EST3 network communication family, enabling secure data and audio transfer between fire alarm control panels. Unlike the 3-RS485A, which offers two Class A audio circuits, the 3-RS485B provides one Class B audio circuit for system integration flexibility. The module supports up to 64 nodes across copper or fiber cabling, with the 3-FIBMB used for fiber communication. Fail-safe circuitry ensures continuous operation by automatically connecting input and output ports if the card or CPU fails, preserving critical communication pathways.
Key Features:
- Network Communications Interface: Provides connectivity between EST3 network nodes.
- Class A/B Network Support: Configurable for Class A (Style 6) or Class B (Style 4) circuits.
- Audio Circuit: One Class B digitized audio circuit for message and paging distribution.
- Message Re-Transmission: Extends circuit length by forwarding network signals to the next node.
- Extended Network Reach: Supports up to 64 nodes and long wiring runs across large facilities.
- Fail-Safe Protection: Direct-connect ports maintain communication if the card or CPU fails.
- Fiber Compatible: Works with the 3-FIBMB for fiber optic media connections.
- Compact Mounting: Installs directly onto the 3-CPU1 processor module.
- Electrical Supervision: Provides isolated and non-isolated network/audio port configurations.
- Reliable Performance: Designed for life safety applications requiring uninterrupted communication.
The 3-RS485B delivers the reliability and fault tolerance required for network and audio communication in Edwards EST3 systems.
