The IS200ISBEH1A is an ISBus Extender Board designed by General Electric (GE) for its control systems. This board is a hardware revision within the ISBE series, serving as an earlier version compared to the IS200ISBEH2A. It is primarily used for connection between an ISBus full duplex source (either a BAIA or an ACL module) and the ISBus. It provides fiberoptic to electrical conversion of RS-485 signals and the capability to bypass a node of the ISBus when either power to the node is interrupted or an interlock connection within the full duplex interface is opened.
The IS200ISBEH1A board plays a critical role in GE control systems as a communication relay and extender. Through its bypass relay, it achieves flexible signal routing: when the board is powered normally and the interlock is closed, it connects the transmit signals from the full duplex input (P1A) to the fiber optic transmit output (P2), and simultaneously connects the signal from the fiber optic receive input (P3) to the full duplex output (P1A). When the board is de-energized, it automatically bypasses the signal from the fiber optic receive input (P3) directly to the fiber optic transmit output (P2), implementing node bypass functionality and ensuring uninterrupted communication on the ISBus.
Key features of the IS200ISBEH1A include:
Fiberoptic to Electrical Conversion: Provides bidirectional conversion between RS-485 signals and fiber optic signals.
Node Bypass Function: Automatically bypasses a node when power is lost or the interlock is opened, ensuring uninterrupted ISBus communication.
Long-Distance Communication: Achieves link distances up to 1 km or more when using HCS fiber or 62.5/125 μm glass fiber.
Electrical Isolation: Signal isolation greater than 1 MΩ @ 500 V rms ensures system safety.
Multiple Operating Modes: Supports repeater mode, optical-to-electrical conversion mode, and standard I/O mode.
Status Indication: 4 LED indicators provide status for power, data transmit, interlock status, and optical signal detection.
Flexible Power Options: Can be powered via P1A, P2, or P3, among other methods.
Configurable Interlock: Jumper JP1 allows selection of whether to bypass the external interlock signal.
The board is DIN-rail mounted, with the mounting feet serving as the connection point for chassis ground. The board features five plug connectors, one terminal board, two ST-type fiber optic connectors, and one adjustable jumper. It has no fuses or test points. As an earlier version of the ISBE series, the IS200ISBEH1A, while maintaining core functionality, may have slight differences in certain electrical characteristics or compatibility compared to the H2A version.
II. Main Functions
The primary functions of the IS200ISBEH1A include, but are not limited to, the following:
1. Signal Conversion and Routing
The core function of the IS200ISBEH1A board is to convert and route ISBus signals between electrical and optical forms. It supports the following signal paths:
Normal Mode (Node not bypassed): Transmit data from P1A (electrical) is converted to an optical signal and output from U9 (TX); received optical data from U5 (RX) is converted to an electrical signal and output from P1A.
Bypass Mode (Node bypassed): Received optical data from U5 (RX) is directly converted to an optical signal and output from U9 (TX), bypassing the local node.
2. Node Bypass Protection
If 24 V dc is not supplied to the ISBE board, the board automatically enters bypass mode:
The transmit connection between P1 and P2 is interrupted (broken).
The receive connection between P3 and P1 is interrupted (broken).
A connection is established between U5 (RX) and U9 (TX), where received optical input data is converted to electrical signals, optionally retimed, and reconverted to an optical output signal.
This design ensures that even if a node loses power, the ISBus communication link remains uninterrupted, enhancing system reliability.
3. Long-Distance Fiber Optic Communication
The optical inputs and outputs are compatible with 200 μm HCS fiber or 62.5/125 μm glass fiber, using ST-type connectors. The optical performance meets that of a transmitter/receiver pair that provides at least a 1 km link when used with either an HCS fiber optic cable or a 62.5/125 μm glass fiber.
4. Transmit Signal Conditioning
Transmit signal conditioning consists of input signal isolation and termination, bypass multiplexing, and electrical-to-optical signal conversion. Signal isolation is greater than 1 Megohm at 500 V rms for one second. The input termination is 100 Ω ±10%.
Bypass multiplexing provides connectivity as follows:
5. Receive Signal Conditioning
Receive signal conditioning provides output signal isolation, bypass multiplexing, and optical-to-electrical signal conversion. Signal isolation is greater than 1 Megohm at 500 V rms. The receiver circuitry is capable of driving a transformer-coupled output load with a 100 Ω ±10% resistive termination while still meeting RS-485 specifications. The receiver output does not present any differential DC levels on its output.
Bypass multiplexing provides connectivity as follows:
6. Multiple Operating Modes
The IS200ISBEH1A supports three operating modes:
Repeater Mode: Relay de-energized; no jumper on P1A-4,5; no jumper between JP1-2,3; power supplied via P3; uses only fiber optic I/O.
Optical-to-Electrical Converter Mode: Uses optical input and electrical output on P1A-3,6, or uses electrical input on P1B-3,6 and optical output; relay must be energized (apply 24V between JP1-2,3); power supplied via P2.
Standard I/O Mode: Connect backplane or ACL to P1; provide relay power via P1-7,8 or P2-1,2; jumper P1A-4,5 for interlock; power supplied via P3.
7. Power Supply Flexibility
The onboard DC-DC converter accepts an input voltage of 18 to 36 V dc and has a maximum input power requirement of 5 watts. Power can be provided via multiple methods:
P1A-7,8 (from backplane or ACL).
P2 (auxiliary interlock power).
P3 (board electronics power).
III. System Applications
1. Application in ISBus Communication Extension
The IS200ISBEH1A is a key board for extending ISBus communication distance and increasing node flexibility within GE control systems. Its roles within the system include:
Communication Relay: Acts as a repeater in long-distance ISBus communication, extending the communication range.
Node Bypass: Automatically bypasses a node upon power loss or failure, ensuring uninterrupted bus communication.
Media Conversion: Provides conversion between electrical RS-485 signals and fiber optic signals, offering electrical isolation and noise immunity.
Network Expansion: Allows adding more nodes to the ISBus while maintaining communication reliability.
2. Coordination with BAIA and ACL
The IS200ISBEH1A can be connected between an ISBus full duplex source (BAIA or ACL module) and the ISBus. Through its flexible power and signal routing options, it can adapt to different system configuration requirements.
3. Differences from the H2A Version
As an earlier version, the IS200ISBEH1A is largely similar in core functionality to the H2A version, but potential differences may include:
Slight variations in certain electrical characteristics.
An earlier firmware version that may not support some later-added features.
Potentially slight performance differences under extreme environmental conditions.
Users should verify compatibility based on specific system requirements when selecting.
4. Typical Application Scenarios
Long-Distance ISBus Communication: Used in power plants, industrial facilities, and other locations requiring long-distance communication to extend ISBus range using fiber optics.
High-Reliability Control Systems: In applications demanding high availability, the node bypass function prevents single points of failure from causing communication interruptions.
Applications Requiring Electrical Isolation: Used where strong electrical isolation is needed, providing isolation between ISBus devices via fiber optics.
Harsh Environment Applications: In industrial environments with high electromagnetic interference, fiber optic communication improves signal integrity.
IV. Detailed Interface Description
1. P1A Full Duplex Connector
P1A is an 8-pin RJ45 shielded connector for connecting a full duplex source (BAIA or ACL). Pin assignments are as follows:
| Pin | Nomenclature | Description |
|---|
| 1 | XMIT DATA IN+ | Positive RS-422 input |
| 2 | XMIT DATA IN- | Negative RS-422 input |
| 3 | RECV DATA OUT+ | Positive RS-422 output |
| 4 | RELAY INTERLOCK | Routing of 24 V dc to the full duplex source |
| 5 | RELAY INTERLOCK RTN | Routing of 24 V dc back from the full duplex source to energize the relay(s) |
| 6 | RECV DATA OUT- | Negative RS-422 output |
| 7 | INTERLOCK 24VDC | 24 V dc input |
| 8 | INTERLOCK 24VDC RTN | 24 V dc return |
2. P1B Auxiliary Transmit Connector
P1B is an 8-pin RJ45 shielded connector for applications that use the board for only fiber-optic to electrical conversion and do not use P1A. Only pins 3 and 6 are used:
| Pin | Nomenclature | Description |
|---|
| 1,2 | N/C | Not Connected |
| 3 | XMIT DATA IN+ | Positive RS-485 input |
| 4,5 | N/C | Not Connected |
| 6 | XMIT DATA IN- | Negative RS-485 input |
| 7,8 | N/C | Not Connected |
3. P2 Auxiliary Interlock Power Connector
P2 is a 2-pin screw terminal connector for connecting an auxiliary/external power source:
| Pin | Nomenclature | Description |
|---|
| 1 | AUX INTERLOCK 24VDC | 24 V dc from an auxiliary/external power source |
| 2 | AUX INTERLOCK 24VDC RTN | 24 V dc return |
4. P3 Board Electronics Power Connector
P3 is a 2-pin screw terminal connector for powering the active components on the board:
| Pin | Nomenclature | Description |
|---|
| 1 | 24VDC MODULE POWER | 24 V dc power to the active components on the board |
| 2 | 24VDC MODULE POWER RTN | 24 V dc return |
Note: This power should come from an independent power supply to maintain power to the board in case the power to the cabinet is removed.
5. Fiber Optic Connectors
| Connector | Description |
|---|
| U5 | Receive data interface to ISBus (ST type) |
| U9 | Transmit data interface to ISBus (ST type) |
V. LED Indicators and Jumper Configuration
1. LED Indicators
| LED | Color | Nomenclature | Description |
|---|
| DS1 | Green | POWER | Indicates that 24 V dc is available for powering the module |
| DS2 | Yellow | XMIT DATA IN | Indicates the presence of transmit data input (from P1) |
| DS3 | Green | INTERLOCK ACTIVE | Indicates that the bypass relay is energized |
| DS4 | Green | DETECT | Indicates that correct optical data is being received |
2. Jumper JP1 Configuration
| Position | Description |
|---|
| 1-2 | Default position; board must have the external interlock closed to energize the relay(s) |
| 2-3 | Shorts out the interlock; power must be supplied to the board through P1-7,8 or P2-1,2 to energize the relay(s) |
VI. Installation and Maintenance
1. Mounting Location
The IS200ISBEH1A board is DIN-rail mounted, with the mounting feet serving as the connection point for chassis ground. It should be installed in an accessible location within the control cabinet for easy connection and maintenance of fiber optic cables.
2. Installation Steps
Install DIN Rail: Ensure the DIN rail is securely mounted inside the cabinet.
Mount Board: Snap the IS200ISBEH1A board onto the DIN rail.
Ground Connection: Ensure good contact between the mounting feet and the cabinet chassis ground.
Connect Power: Select P1A, P2, or P3 for power supply as required.
Connect ISBus Cables: Connect the full duplex source to P1A, or connect the auxiliary transmit source to P1B.
Connect Fiber Optics: Connect the ISBus fiber optic cables to U5 (RX) and U9 (TX).
Configure Jumper: Set JP1 according to system requirements.
Check LEDs: After power-up, verify that the LEDs indicate normal status.
3. Maintenance Recommendations
Periodic Inspection: Check fiber optic connectors for cleanliness and secure connections.
Cleaning: Regularly clean the board to prevent dust accumulation.
ESD Protection: Wear a grounding strap when handling the board and store it in anti-static bags.
Spare Parts Management: Maintain a spare ISBEH1A board to reduce downtime in case of failure.
