Multi-Drop Fiber Optic Data Multiplexer w/Self-Healing Ring (4/8/12 ch.)

• Sophisticated Self-Healing Ring
• All Digital Design
• Hardened Temperature version exceeds NEMA & CALTRANS specs
• Protocol Transparent
• Separate Broadcast/Receive Channels
• RS-232, RS-422, RS-485 (2/4-wire)
• Multimode (850/1300nm) or Single Mode (1300/1550nm)
• Built-In Power Redundancy
• Optical Loop Integrity Test
• Local Dry Contact Alarm Relay
• Rackmount or Standalone

The TC2800 is frequently used to interconnect Remote Terminal Units (RTUs) or Programmable Logic Controllers (PLCs) in Utility substation SCADA Networks that require multiple channels. It is also used for similar connectivity applications in Traffic Control, Industrial Process Control and Security System Networks.

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Self-Healing Ring

A Self-Healing Ring (also called Dual Ring or Counter-Rotating Ring) topology provides maximum fault tolerance and network flexibility.

It consists of two data paths, Ring A and Ring B, with each data path running in an opposite direction to the other.

Under normal operation only the primary data path (Ring A) is used. When there is fault (cable or failed device), the data path will turn around before it reaches the fault of failed unit and use the secondary data path to complete the link. In this manner, the data path to the remainder of the units will remain intact.

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The TC2800's most reliable configuration is the "multiple master" Self- Healing Ring.

This innovative configuration maximizes the reliability of a single Master because it can recover faults or failures in both rings in multiple places.

During normal operation, Master # 2 is set in a "THRU" mode via a DIP switch at the front panel.

When a double fault (all four fiber optic cables in a fault condition) occurs (see figure), Master #2 is switched back to "MASTER" mode. In the "MASTER" mode, the broadcast messages are sent through Master #1 and Master #2 at the same time. The responses from the slave units are also received by Master’s #1 and #2.

In extreme situations where both rings are broken in two separate places, both Master units poll the Slaves at the same time, but through different “half” rings.

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In many traffic control applications, the TC2800 can be used as a low cost alternative to SONET or T1 Rings. The diagram to the right illustrates how the TC2800 can create a self-healing ring network for linking traffic intersections with multiple RS-232 drops for traffic lights, cross walks, camera PTZ, etc.

High speed SONET networks are often expensive and the TC2800 easily provides the desired ring fault protection

A similar application uses the TC2800 to link PTZ, radar detectors, ramp meters, weather stations, etc. along a stretch of highway.

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The diagram to the right illustrates a Distribution Automation Network (DAN) with a Self-Healing Ring topology over a distance of about 100 kilometers. The DAN includes Automated Meter Reading and telephone extentions (TC1900’s).

It uses a TC2800 Master multi-drop multiplexer at the main office and TC2801 slave muxes at each of the other sites.

The DAN uses four asynchronous 38.4 kbps data channels. To speed up the SCADA polling process (which runs at 9600 kbps), the master station at the main office communicates simultaneously with onehalf of the Remote Terminal Units (RTUs) on channel 1, the other half on channel 2.

The DAN uses channel 3 for an Automated Meter Reading (AMR) system capable of reading meters manufactured by multiple vendors, again at 9600 bps. Channel 4 is used for telephone extension and channel 5 is RS-485 AMR test applications. The integrity of the DAN is monitored entirely through the SCADA system.

Sample Application #3
Telephone & Data Application

The TC2800 can multiplex both telephone and data by using the "Quick-Talk" RS-232 Telephone Extender. Quick-Talk is compatible with most analog PBXs and enables dial-up telephone extensions to be plugged into most RS-232 circuits.

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