The GE IS200TDBTH6AAA Discrete I/O Terminal Board is a triple modular redundant (TMR) discrete input and output terminal board used within GE Industrial Control Systems. As a member of the TDBT board family, the IS200TDBTH6AAA Discrete I/O Terminal Board is designed for TMR redundancy with either DIN-rail or flat mounting. Three PDIO I/O packs plug into D-type connectors and communicate with the controllers over Ethernet, providing the redundant architecture required for critical control applications.
The IS200TDBTH6AAA Discrete I/O Terminal Board accepts 24 group-isolated contact inputs that are supplied with a nominal 125 V DC wetting voltage from an external source, with an operating range of 100 to 145 V DC. The contact inputs have noise suppression to protect against surge and high-frequency noise. The board provides 12 form-C relay outputs and accepts the WROB option board to expand relay functions, and all terminal board versions have pluggable terminal blocks.
The IS200TDBTH6AAA Discrete I/O Terminal 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 "TDBT" acronym identifies the board's functional designation as a Discrete I/O Terminal Board. The "H6" designation identifies the hardware group and the 125 V DC wetting voltage variant, while the "AAA" 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 IS200TDBTH6AAA Discrete I/O Terminal Board is specifically the H6A version of the TDBT family, providing a nominal 125 V DC floating wetting voltage ranging from 100 to 145 V DC. The TDBT family also includes the H2A version with a nominal 24 V DC wetting voltage, the H4A version with a nominal 48 V DC wetting voltage, and the H8A version with a nominal 24 V DC wetting voltage that is specifically designed for use in hazardous locations. The H6A version is widely used in applications that require 125 V DC contact wetting voltage for compatibility with station battery systems and high-voltage control circuits.
This product introduction provides detailed technical information, functional descriptions, connector assignments, configuration guidance, and comprehensive specifications for the GE IS200TDBTH6AAA Discrete I/O Terminal 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 IS200TDBTH6AAA Discrete I/O Terminal Board is built around a robust TMR discrete input and output architecture that combines 24 group-isolated contact inputs with 12 form-C relay outputs, providing redundant discrete interfacing for a wide range of field devices. The board performs several distinct functions that ensure reliable and accurate acquisition of discrete signals and control of relay outputs in electrically noisy industrial environments.
The 24 contact inputs of the IS200TDBTH6AAA Discrete I/O Terminal Board are supplied with a nominal 125 V DC wetting voltage from an external source, with an operating range of 100 to 145 V DC. The threshold voltage is 50% of the wetting voltage, providing a well-defined and noise-immune switching point. Contact input currents are resistance-limited to 2.55 mA on the first 21 circuits and 10 mA on circuits 22 through 24, allowing the board to accommodate a wide range of contact types. The AC voltage rejection is 60 V RMS at 125 V DC wetting voltage, providing excellent immunity to AC noise superimposed on the DC input signals.
Filters reduce high-frequency noise and suppress surge on each input near the point of signal entry, ensuring that only valid contact transitions are reported to the I/O processor. The discrete input voltage signals go to the I/O processor, which passes them through optical isolators, converts them to digital signals, and transfers them to the controller. The contact input function and on-board signal conditioning are the same as those on the STCI board, providing consistency across the GE control system family.
The 12 form-C relay outputs of the IS200TDBTH6AAA Discrete I/O Terminal Board provide normally open, normally closed, and common contacts for each relay, along with a solenoid return circuit path for a solenoid that is powered by the relay board. The relay portion of the board does not change between groups H2A, H4A, and H6A, only the contact input circuits change, so the relays may be used at any specified AC or DC voltage without regard to board group. The relay outputs have a maximum response time of 25 ms on and 25 ms off, a silver-nickel alloy contact material, and a contact life of 100,000 electrical operations and 5,000,000 mechanical operations.
TMR Redundancy Architecture
The IS200TDBTH6AAA Discrete I/O Terminal Board is specifically designed for TMR redundancy, providing three connection points for the PDIO I/O packs. With dual controllers, the PDIO on the TDBT connector JR1 would be networked to the R controller, the JS1 PDIO to the S controller, and the JT1 PDIO to both the R and S controllers. With TMR controllers, one network connection is provided to each PDIO leading to the respective controller, providing the redundant communication paths required for the TMR architecture.
The TDBT board is not designed to operate correctly with a single PDIO I/O pack, because the TMR architecture requires all three PDIO packs to be present for the voting and redundancy functions to operate correctly. This requirement ensures that the TMR system maintains its fault tolerance and that a single PDIO failure does not compromise the discrete input and output functions.
The relay outputs of the IS200TDBTH6AAA Discrete I/O Terminal Board include a voting function, with the three PDIO packs voting on the correct relay state and the voted result being used to drive the relay. This voting architecture ensures that a fault in one PDIO pack does not cause an incorrect relay output, providing the high availability required for critical control applications.
Option Board and Relay Expansion
The IS200TDBTH6AAA Discrete I/O Terminal Board accepts the WROBH1A option board, which plugs into the TDBT connectors JW1 and JW2 and is held in place by the force of the connectors. The WROBH1A option board adds capability to the TDBTH2A, H4A, and H6A to yield a combination that has the same relay circuit functionality as an IS200TRLYH1B terminal board when used in a TMR system.
The WROBH1A option board includes fused sensed power distribution to the first six relay contacts and dedicated power to the last relay contact. Both sides of the power distribution on relays 1 through 6 are fused, allowing the board to be used in systems where DC power is floating with respect to earth. Fuse voltage feedback is compatible with 24 V, 48 V, and 125 V DC applications as well as 120 V and 240 V AC applications. The WROBH1A has a default fuse value of 3.15 A and includes six jumpers that are used to apply or remove power from a relay, with all six jumpers in place at the factory and removed when a relay is to be used as dry contacts without power distribution.
It is important to note that the WROFH1A and WROGH1A option boards are not compatible with the TDBT terminal board, so only the WROBH1A option board should be used with the IS200TDBTH6AAA Discrete I/O Terminal Board. Additionally, discrete output option boards such as the WROBH1A are not HazLoc certified and shall not be used with TDBS or TDBT terminal boards in hazardous (classified) locations.
Installation and Wiring
The IS200TDBTH6AAA Discrete I/O Terminal Board is designed for flexible installation in standard industrial cabinets. The board plus a plastic insulator mounts on a sheet metal carrier that then mounts on a DIN rail, or optionally the board plus insulator mounts on a sheet metal assembly that then bolts in a cabinet. The connections are wired directly to two sets of 48 terminal blocks, typically using #24 to #12 AWG wires. The upper set of terminals, TB1, connects to the relay portion of the board, and the lower set of terminals, TB2, connects to the contact input circuits. Screw assignments for the two sets of terminals are identical to those found on the SRLY relay board and the STCI contact input terminal board, providing consistency and simplifying migration between board families. Shields should be terminated on a separate bracket.
For the TDBTH2A, TDBTH4A, and TDBTH6A boards, the wetting voltage output terminals are all in parallel and fed from the positive voltage applied to JE1 pin 1. It is permissible to run a single wetting voltage lead from the board terminal to a group of remote contacts and then bring the individual contact wires back to the inputs. Negative or return wetting voltage is supplied by JE1 pin 3. For the TDBTH8A, each wetting voltage output terminal is protected by a separate internal current limit resistor, so a separate wetting voltage lead must be run for each individual output.
The contact input connections are made to the 48 terminals on the lower portion of the terminal board, grouped as TB2, with contact wetting voltage provided to the board through the JE1 3-pin Mate-N-Lok connector on the lower portion of the board. The terminal assignments for the contact inputs are clearly defined, with each input having a corresponding wetting voltage terminal and input terminal, allowing straightforward field wiring.
Diagnostics and Fault Detection
The IS200TDBTH6AAA Discrete I/O Terminal Board provides comprehensive diagnostic capabilities that assist with system verification and fault isolation. The PDIO I/O packs monitor several functions on the TDBT, including the contact wetting voltage, which is monitored and generates a diagnostic alarm if the wetting voltage drops to below 40% of the nominal voltage. The diagnostic alarm is set and latched, alerting the operator to a potential problem with the wetting voltage supply.
The TDBT provides diagnostic feedback to the PDIO indicating the state of each relay by monitoring an isolated set of contacts on each relay. Position feedback is fanned out to all three PDIOs, allowing each PDIO to verify the relay state independently. When the WROBH1A option board is used with the TDBT, isolated voltage feedback is used to detect fuse status for the six fuse pairs on the board, and the TDBT provides this feedback to all three PDIO packs.
Each terminal board I/O pack connector has an ID device that is interrogated by the PDIO. The connector ID is coded into a read-only chip containing the board serial number, board type, and revision number. The WROBH1A option board contains three ID devices, one for each PDIO, and if a mismatch between the I/O pack, terminal board, or option card is encountered, a hardware incompatibility fault is created, preventing the system from operating with incorrect or mismatched hardware.
The fault detection capabilities of the IS200TDBTH6AAA Discrete I/O Terminal Board also include loss of contact input wetting voltage and non-responding contact input in test mode, providing comprehensive coverage of the most common failure modes in discrete input and output circuits.
Configuration
The IS200TDBTH6AAA Discrete I/O Terminal Board has no jumpers or hardware settings on the board itself. Configuration is performed through the system software and the PDIO I/O packs, simplifying installation and reducing the potential for configuration errors. The option board WROBH1A includes six jumpers that are used to apply or remove power from a relay, with the jumpers removed from the board when a relay is to be used as dry contacts and power distribution is not desired.
Application Suitability and System Integration
The IS200TDBTH6AAA Discrete I/O Terminal Board is a versatile TMR discrete interface that can be used in a wide variety of GE Industrial Control System applications. Its 24 contact inputs with 125 V DC wetting voltage make it suitable for monitoring limit switches, pressure switches, level switches, temperature switches, relay contacts, pushbuttons, and other discrete field devices in applications where the control system uses a 125 V DC station battery or other high-voltage DC control supply. Its 12 form-C relay outputs provide normally open, normally closed, and common contacts for controlling pilot relays, interposing relays, contactors, solenoid valves, indicator lamps, and other discrete output devices.
The board's TMR architecture, with three PDIO I/O packs and voting on the relay outputs, provides the fault tolerance and high availability required for critical control applications. The board's support for the WROBH1A option board allows the relay functions to be expanded with fused and sensed power distribution to the first six relay outputs and dedicated power to the last relay output, and the option board's isolated voltage feedback allows the control system to detect fuse status and relay state, providing comprehensive diagnostics for the discrete input and output circuits.
In GE Industrial Control System applications, the IS200TDBTH6AAA Discrete I/O Terminal Board works with three PDIO I/O packs, which plug into the D-type connectors and communicate with the controllers over Ethernet. The board's pluggable terminal blocks and clearly labeled connectors simplify installation, verification, and maintenance, and the comprehensive diagnostics, including wetting voltage monitoring, relay state feedback, and fuse status monitoring, ensure that faults are detected and reported.
The board's support for DIN-rail or flat mounting and direct cabinet bolt-on provides flexibility for different cabinet arrangements, and the use of #24 to #12 AWG wires accommodates a wide range of field wiring sizes. The shield termination on a separate bracket ensures proper shielding and grounding of the field wiring, contributing to reliable operation in electrically noisy industrial environments.
Maintenance and Lifecycle
The IS200TDBTH6AAA Discrete I/O Terminal Board is designed for long service life with minimal maintenance. The board contains no moving parts other than the relays, and its robust construction and surface-mount technology ensure high reliability in continuous industrial operation. Routine maintenance consists of periodic visual inspection of the board, terminal blocks, and wiring, verification that the wetting voltage is present and within specification, and confirmation that the shield terminals are properly connected.
The board's diagnostic features, including the wetting voltage monitoring, the relay state feedback, the fuse status monitoring, and the onboard ID chip, simplify troubleshooting and ensure that the correct board and option cards are installed in each location. If the wetting voltage drops below 40% of nominal, the board sets and latches a diagnostic alarm, protecting the system from incorrect operation. If a fuse opens in the WROBH1A option board, the isolated voltage feedback detects the open fuse and generates a diagnostic, allowing the maintenance technician to quickly identify and replace the failed fuse.
If the board requires replacement, the process is straightforward. After de-energizing the associated equipment and verifying that no power exists, the pluggable terminal blocks should be labeled and removed, and the board should be removed from its mounting. The replacement board should be installed in the same position, and the terminal blocks reconnected as labeled 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 IS200TDBTH6AAA Discrete I/O Terminal 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 IS200TDBTH6AAA Discrete I/O Terminal Board is a reliable, robust, and versatile TMR discrete interface for GE Industrial Control Systems. Its 24 contact inputs with 125 V DC wetting voltage, its 12 form-C relay outputs with voting across three PDIO packs, its support for the WROBH1A option board with fused power distribution and fuse status monitoring, and its comprehensive diagnostics provide the flexibility, fault tolerance, and reliability required for a wide range of critical industrial discrete input and output applications.
With its pluggable terminal blocks, clearly labeled connectors, comprehensive diagnostics, TMR redundancy, and compatibility with the PDIO I/O packs, the IS200TDBTH6AAA Discrete I/O Terminal Board is designed for easy installation, verification, and maintenance. Backed by GE's quality manufacturing, global support network, and commitment to backward compatibility, the IS200TDBTH6AAA Discrete I/O Terminal 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 IS200TDBTH6AAA Discrete I/O Terminal Board provides the discrete input and output functionality required for reliable and efficient control system operation.
