Self-Healing Ring Multi-Drop Fiber Optic Modem (RS232/422/485)

• Async Data Rates up to 38.4 Kbps
• Protocol Transparent
• All-Digital Design
• Multiple Master Capability
• Multimode (850/1300nm) or Single Mode (1300/1550nm)
• RS-232, RS-422 or RS-485 (2/4-wire)
• Local and Remote Loopback Tests
• Optical Loop Integrity Test
• Anti-Streaming (Anti-Jabber)
• Local Dry Contact Alarm Relay
• Hardened Temperature Versions (optional)
• Hi-Temp2 Version Exceeds NEMA & Caltrans Traffic Control Specs

Renowned for its high reliability, the TC2100 Multi-Drop Modem is ideal for Ring or Self-Healing Ring communication links in SCADA, Traffic Control, Industrial Process Control and Security Networks. It is frequently used to interconnect Remote Terminal Units (RTUs) or Programmable Logic Controllers (PLCs) in Utility substation SCADA Networks.

Click to enlarge

Click to enlarge

Many of the TC2100’s features are critical to network operation; some are unique for a product of this type. It is important to note that the term "Self-Healing Ring" means different things to different vendors. Because there is no industry standard for Self-Healing Rings, vendor offerings vary greatly in terms of function, features and sophistication.

The TC2100 Self Healing Ring differs from competitor offerings in its sophistication. This sophistication enables it to build in a variety of user benefits often not available with many other vendor’s Self-Healing Rings.

These benefits include:

• The TC2101 Slave Unit Provides Loop Monitor Signal LEDs that Detect if any Incorrect Fiber Cables are Connected.
  Solidly lit green LPA (Loop "A") and LPB (Loop "B") LEDs indicate a normal system; blinking green LEDs indicate that the fiber cables have been cross-connected. Some vendors do not offer any simple means to verify that the fiber optic cables are cross-connected at remote nodes.
  
  This is absolutely critical! For example, if a technician inadvertently cross-connects the Ring A and Ring B cables to a modem, the network will appear to function normally, but the Self-Healing portion will not be operable. Technicians must have specific diagnostics to pinpoint where the errant cable cross-connect has occurred.
  
  
• The TC2100 can Detect Faults Both Upstream and Downstream from Each Unit.
  The TC2100 can detect cable breakage at both transmit and receiving sides. Some vendor's SHR products detect cable breakage only at the receiving side. Unless the device can detect failures at the transmit side, there is no way to know if the next device is receiving the signal (see adjacent diagram).
  
  
  
  Click to enlarge
  
  
  
• The TC2100 Prevents any Type of Echo Effect.
  Some vendors offer a self-healing scheme that doesn't separate broadcast and receive channels. This often results in an "Echo" effect that can disable network communications. ("Echo" happens when the data signal transmitted into the Master unit, and around the ring, is received back at the Master unit’s port).
  
  
• Each TC2101 (Slave) Includes a Dry Contact Alarm which Enables Pinpointing any Fault.
  Technicians must be able to pinpoint exactly where a fault has occurred. A dry alarm contact on the modem's master unit indicates when self healing has occurred somewhere on the ring. Dry alarm contacts from the modem slave units on either side of a fault effectively pinpoint the location of the break or failure (see diagram).
  
  
  
  Click to enlarge
  
  
  
• The TC2100 Offers a Multiple-Master Self- Healing Ring Topology.
  This innovative configuration virtually doubles the reliability of a single Master because it can recover faults or failures in both rings A and B in two different places (See diagram on page 4). System integrity is maintained because both Master units poll the Slaves at the same time, but through different "half" rings.
  
  
• The TC2100 Provides Two Channels for Data, Controls or a Telephone Link (via the TC1900 Telephone Adapter)
  Use two channels for RS-232 or one for RS-422 or RS-485. You can also add telephone service by using the TC1900 RS-232 Telephone Extender. The TC1900 is compatible with most analog PBXs and enables dial-up telephone extensions to be plugged into RS-232 circuits.
  
  
• The TC2100 Provides a Built-In Test Signal Generator to Verify Optical Loop Integrity
  A built-in testsignal generator provides a simple and effective method for a selftest verifying link integrity.
  
  

A Self-Healing Ring 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 or failed unit and use the secondary data path to complete the link. In this manner, the data/communication path remains intact.

A multiple master topology (see diagram below) provides maximum reliability. It can maintain Ring integrity despite faults or failures in both rings in several different places, depending on the number of master units.

For more information