The GE IS200ISBEH2ACC ISBus Extender Board is a specialized fiber-optic interface and network bypass module used within GE Industrial Control Systems. As a member of the ISBE board family, the IS200ISBEH2ACC ISBus Extender Board is connected between an ISBus full duplex source—either a BAIA module or an ACL module—and the ISBus. Its primary function is to provide fiber-optic to electrical conversion of the 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. This extender function is essential for extending the ISBus network over distances that exceed the practical limits of copper cabling, while the bypass function maintains network continuity and availability in redundant or critical control system architectures.
The IS200ISBEH2ACC ISBus Extender Board is identified by the GE part numbering convention used throughout the Industrial Control Systems product line. The "IS200" prefix identifies the board as a GE Industrial Control Systems product, with "200" specifically indicating that the board is a base-level assembly. The "ISBE" acronym identifies the board's functional designation as an ISBus Extender Board. The "H2" designation identifies the hardware group and conformal coating, while the "ACC" suffix identifies the artwork and functional revision combination. All digits are important when ordering or replacing any board, as boards of different revision levels may not contain identical hardware, and GE ensures backward compatibility of replacement boards while noting that different revision levels may not contain identical components.
The IS200ISBEH2ACC ISBus Extender Board operates by means of a bypass relay that connects the transmit signals from either the full duplex input (P1A) or the AUX XMIT DATA IN (P1B) to the fiber-optic transmit output data (P2). This is done through the transmit electrical-to-optical conversion and the optical receive-data-input connector (P3) of the ISBus, to the full duplex connector through the receive optical-to-electrical converter when 24 V DC is available on either P1A or TB2 and the interlock connection on P1A or JP1 is closed. The board includes four LED indicators that indicate power, transmit data input, interlock active, and optical data detect status.
This product introduction provides detailed technical information, functional descriptions, connector assignments, configuration guidance, and comprehensive specifications for the GE IS200ISBEH2ACC ISBus Extender Board, serving as an essential reference for control system engineers, maintenance technicians, and system integrators working with GE industrial control equipment.
Functional Architecture and Signal Processing
The IS200ISBEH2ACC ISBus Extender Board is built around a robust fiber-optic conversion and relay-based bypass architecture that provides deterministic, fail-safe bypass operation along with reliable optical signal transmission. This architecture ensures that the ISBus network can be extended over long distances using fiber-optic cable, while the bypass function operates reliably even under brownout conditions or total loss of power.
The core of the IS200ISBEH2ACC ISBus Extender Board is the bypass relay, which is part of the board and performs the signal routing functions. When 24 V DC is available on either P1A or TB2 and the interlock connection on P1A or JP1 is closed, the bypass relay is energized and connects the transmit signals from either the full duplex input (P1A) or the AUX XMIT DATA IN (P1B) through the transmit electrical-to-optical conversion to the fiber-optic transmit output data (P2), and connects the optical receive-data-input connector (P3) through the receive optical-to-electrical conversion to the full duplex connector. In this normal operating state, the node is fully connected to the ISBus and can transmit and receive data normally over the fiber-optic link.
When the 24 V DC is not supplied to the IS200ISBEH2ACC ISBus Extender Board, the bypass relay drops out and the following occurs: the transmit connection between P1 and P2 is interrupted (broken), the receive connection between P3 and P1 is interrupted (broken), and the connection between the receive input (P3) and the transmit output (P2) is made such that the receive optical input data are converted to electrical signals, optionally retimed, and reconverted to an optical output signal. This loopback configuration effectively removes the failed or isolated node from the ISBus and passes the network signals through to the next node, maintaining the continuity of the ISBus network.
The DC-DC converter on the IS200ISBEH2ACC ISBus Extender Board is capable of accepting an input voltage of 18 to 36 V and has a maximum input power requirement of 5 watts. This wide input voltage range ensures that the board can operate reliably from a variety of power sources, and the low power requirement minimizes the heat dissipation and the load on the power supply.
The optical inputs and outputs of the IS200ISBEH2ACC ISBus Extender Board are compatible with 200 μm Hard Clad Silica (HCS) fiber or 62.5/125 μm glass fiber, and the input/output connectors are ST types. 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. This optical performance enables the ISBus network to be extended over distances of up to 1 km, far exceeding the practical limits of copper-based RS-485 transmission and providing galvanic isolation between the network segments.
The use of HCS fiber or 62.5/125 μm glass fiber provides excellent immunity to electromagnetic interference, ground potential differences, and other electrical noise sources that can degrade copper-based signals in industrial environments. The ST-type connectors are widely available and easy to terminate, simplifying installation and maintenance.
Transmit Signal Conditioning
The transmit signal conditioning of the IS200ISBEH2ACC ISBus Extender Board 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 to any other terminal, providing excellent isolation between the ISBus signals and the board's internal circuitry. The input termination is 100 ohms (±10%), ensuring proper impedance matching and minimizing signal reflections.
The bypass multiplexing provides connectivity as follows: from the transmit data input (electrical) to the transmit data output (optical) when the node is not being bypassed, and from the receive data input (optical) to the transmit data output (optical) when the node is being bypassed. This multiplexing arrangement ensures that the transmit path is correctly routed in both the normal and bypass states, maintaining the integrity of the ISBus network.
Receive Signal Conditioning
The receive signal conditioning of the IS200ISBEH2ACC ISBus Extender Board provides output signal isolation, bypass multiplexing, and optical-to-electrical signal conversion. Signal isolation is greater than 1 megohm at 500 V RMS for one second, and the receiver circuitry is capable of driving a transformer-coupled output load with a 100 ohm (±10%) resistive termination and still meeting the RS-485 specifications. The receiver output does not present any differential DC levels on its output.
The bypass multiplexing provides connectivity as follows: from the receive data input (optical) to the receive data output (electrical) when the node is not being bypassed, and from the receive data input (optical) to the transmit data output (optical) when the node is being bypassed. This arrangement ensures that the receive path is correctly routed in both the normal and bypass states, maintaining the integrity of the ISBus network.
Operating Modes
The IS200ISBEH2ACC ISBus Extender Board supports three distinct operating modes, each of which is configured through the connectors, jumpers, and power connections on the board.
In the repeater mode, the relay is kept de-energized by not jumpering P1A-4,5 and not placing a jumper between JP1-2,3. Power is supplied to the module by applying 24 V between P3-1,2, and only the fiber-optic I/O is used. This mode is useful for extending the ISBus network over long distances without connecting to a copper-based node.
In the optical-to-electrical converter mode, the optical-in/electrical-out path uses the optical input and Pair #2 DATA OUT (P1A-3,6), while the optical-out/electrical-in path uses the AUX DATA INPUT (P1B-3,6) and the optical output. The relay must be energized by applying 24 V between JP1-2,3, and power is supplied to the module by applying 24 V between P2-1,2. This mode is useful for converting between optical and electrical ISBus segments.
In the standard I/O mode (backplane or ACL connection), the backplane or ACL is connected to P1, power for the relay is provided by the backplane interface using 24 V DC from the HFPA via P1-7,8 or by the ACL interface using 24 V DC from the HFPA via P2-1,2, and the interlock for the relay is provided by jumpering P1A-4,5 on the backplane or ACL. Power is supplied to the module by applying 24 V between P3-1,2. This mode is useful for connecting the ISBus Extender Board to a standard backplane or ACL node.
LED Indicators
The IS200ISBEH2ACC ISBus Extender Board includes four LED indicators that provide clear visual indication of the board's status. The green LED (DS1), POWER, indicates that 24 V DC is available for powering the module. The yellow LED (DS2), XMIT DATA IN, indicates the presence of transmit data input from P1. The green LED (DS3), INTERLOCK ACTIVE, indicates that there is power to the bypass relay. The green LED (DS4), DETECT, indicates that correct optical data is being received. These indicators allow maintenance personnel to quickly assess the operating state of the board and to identify the source of a fault.
Connector Assignments and Interfaces
The IS200ISBEH2ACC ISBus Extender Board includes five plug connectors, one terminal board, and two fiber-optic connectors. The P1A connector is an RJ45 shielded full duplex connector with eight pins: pin 1 is XMIT DATA IN+ (positive RS-422 input), pin 2 is XMIT DATA IN− (negative RS-422 input), pin 3 is RECV DATA OUT+ (positive RS-422 output), pin 4 is RELAY INTERLOCK (routing of the 24 V DC to the full duplex source), pin 5 is RELAY INTERLOCK RTN (routing of the 24 V DC back from the full duplex source to energize the relay or relays), pin 6 is RECV DATA OUT− (negative RS-422 output), pin 7 is INTERLOCK 24VDC (24 V DC input), and pin 8 is INTERLOCK 24VDC RTN (24 V DC return).
The P1B connector is an RJ45 shielded auxiliary transmit data connector with eight pins: pins 1 and 2 are not connected, pin 3 is XMIT DATA IN+ (positive RS-485 input), pins 4 and 5 are not connected, pin 6 is XMIT DATA IN− (negative RS-485 input), and pins 7 and 8 are not connected. This connector is used for applications that use the board for only fiber-optic to electrical conversion and do not use P1A.
The P2 connector is the auxiliary interlock power connector with screw terminals: pin 1 is AUX INTERLOCK 24VDC (24 V DC from an auxiliary or external power source) and pin 2 is AUX INTERLOCK 24VDC RTN (24 V DC return from an auxiliary or external power source). The P3 connector is the board electronics power connector with screw terminals: pin 1 is 24VDC MODULE POWER (24 V DC power to the active components on the board) and pin 2 is 24VDC MODULE POWER RTN (24 V DC return). This power should come from an independent power supply to maintain power to the board in case the power to the cabinet is removed.
The U5 and U9 connectors are the ISBus fiber-optic connectors (Type ST): U5 is the receive data interface to the ISBus and U9 is the transmit data interface to the ISBus. The JP1 jumper is the interlock bypass jumper: position 1-2 is the default position, which means the board must have the external interlock closed to energize the relay or relays; position 2-3 shorts out the interlock, although power will have to be supplied to the board through P1-7,8 or TB2-1,2 to energize the relay or relays.
Application Suitability and System Integration
The IS200ISBEH2ACC ISBus Extender Board is an essential component in GE Industrial Control Systems that use the ISBus network for communication between control nodes over long distances. Its ability to convert between electrical RS-485 signals and fiber-optic signals allows the ISBus network to be extended over distances of up to 1 km, far exceeding the practical limits of copper-based transmission, while providing galvanic isolation and immunity to electromagnetic interference.
The IS200ISBEH2ACC ISBus Extender Board is typically installed between an ISBus full duplex source, such as a BAIA module or an ACL module, and the ISBus. When the source is powered and the interlock is closed, the bypass relay is energized and the source is fully connected to the ISBus through the fiber-optic link, allowing normal communication. If the source loses power or the interlock is opened, the bypass relay drops out and the source is automatically bypassed, with the receive optical input converted to electrical, optionally retimed, and reconverted to an optical output so that the network signals pass through to the next node.
The board's DIN-rail mounting and the mounting feet that serve as the chassis ground connection simplify installation in standard control cabinets, and the four LED indicators provide clear visual indication of the board's status. The board's three operating modes—repeater, optical-to-electrical converter, and standard I/O—provide flexibility in configuring the ISBus network for different topologies and requirements.
Maintenance and Lifecycle
The IS200ISBEH2ACC ISBus Extender Board is designed for long service life with minimal maintenance. The board contains one relay as its only moving part, and its solid-state optical conversion circuitry and minimal component count ensure high reliability in continuous industrial operation. Routine maintenance consists of periodic visual inspection of the board, connectors, fiber-optic cables, and LED indicators, and verification that the bypass relay is operating correctly by checking the LED indications and, if necessary, testing the bypass function during a scheduled outage.
The four LED indicators on the IS200ISBEH2ACC ISBus Extender Board provide clear visual indication of the board's power, transmit data input, interlock active, and optical data detect status. If the POWER LED is off, the maintenance technician should check the 24 V DC module power at P3-1, P3-2. If the XMIT DATA IN LED is off when it should be on, the technician should check the P1A or P1B connection and the full duplex source. If the INTERLOCK ACTIVE LED is off when it should be on, the technician should check the 24 V DC interlock power at P1A-7, P1A-8 or TB2-1, TB2-2, and verify that the interlock on P1A is closed or that the JP1 jumper is properly configured. If the DETECT LED is off when it should be on, the technician should check the fiber-optic cables and the remote transmitter.
If the board requires replacement, the process is straightforward. After de-energizing the associated equipment and verifying that no power exists, the connectors and fiber-optic cables should be labeled and disconnected, and the board should be removed from its DIN-rail mounting. The replacement board should be installed in the same position, the connectors and fiber-optic cables reconnected as labeled, and the bypass and communication functions verified before returning the system to service.
GE Industrial Control Systems ensures compatibility of its replacement boards, even though boards of different revision levels may not contain identical hardware. When ordering a replacement IS200ISBEH2ACC ISBus Extender Board, provide the complete part number and description, the drive or system serial number, and the Material List (ML) number. The factory may substitute later versions based on availability and design enhancements, but backward compatibility of replacement boards is guaranteed.
Conclusion
The GE IS200ISBEH2ACC ISBus Extender Board is a reliable, robust, and essential fiber-optic interface and network bypass module for GE Industrial Control Systems that use the ISBus network. Its fiber-optic to electrical conversion of RS-485 signals, relay-based bypass architecture, three operating modes, and clear LED indicators provide reliable long-distance extension of the ISBus network along with automatic bypass of failed or isolated nodes, ensuring that the control system maintains high availability.
With its comprehensive connector set, configurable interlock bypass jumper, DIN-rail mounting, and clearly marked LED indicators, the IS200ISBEH2ACC ISBus Extender Board is designed for easy installation, verification, and maintenance. Backed by GE's quality manufacturing, global support network, and commitment to backward compatibility, the IS200ISBEH2ACC ISBus Extender Board continues to deliver the performance, durability, and reliability that industrial users expect from GE. Whether used in a new installation or as a replacement for an existing board, the IS200ISBEH2ACC ISBus Extender Board provides the fiber-optic extension and network bypass functionality required for reliable and efficient control system operation.
