The IS200SRTDH2A is a compact, high-density simplex Resistance Temperature Detector (RTD) input terminal board within the General Electric (GE) Mark VIe control system. As a member of the SRTD family, the IS200SRTDH2A is specifically designed to connect to the PRTD I/O processor pack, providing 8 channels of three-wire RTD input for industrial process control. It accurately converts the resistance signals from field temperature sensors into digital temperature values usable by the controller. Featuring a convenient pluggable Euro-block terminal design and supporting both DIN-rail and flat mounting, this board is an ideal front-end acquisition device for temperature monitoring and protection loops in power generation, petrochemical, and steel industries.
The core advantages of the IS200SRTDH2A lie in its compact size, flexible mounting methods, and reliable signal conditioning capabilities. It integrates 8 RTD input channels onto a dimensionally optimized board, working in conjunction with the PRTD I/O pack to seamlessly connect to the Mark VIe control network via Ethernet. This achieves an integrated digital chain from the field temperature sensor to the controller. The pluggable terminal design makes field wiring and board replacement extremely convenient, significantly reducing maintenance downtime.
System Positioning and Compatibility
Within the Mark VIe control architecture, the IS200SRTDH2A serves as part of the process I/O subsystem, positioned between the controller's Ethernet network and the field temperature sensors. Its operating mode is as follows: the PRTD I/O pack plugs directly into the DC-37 pin connector on the IS200SRTDH2A board and exchanges high-speed data with the controller via dual RJ-45 Ethernet ports. One IS200SRTDH2A corresponds to one PRTD I/O pack, forming a compact simplex temperature acquisition unit.
The IS200SRTDH2A supports only simplex operation and does not support Triple Modular Redundant (TMR) applications, making it suitable for temperature monitoring loops that are cost-sensitive or have less stringent redundancy requirements. The compatible PRTD I/O pack communicates with the controller over Ethernet, supporting redundant dual network ports for communication reliability. One PRTD I/O pack can handle 8 RTD inputs. If 16 RTD inputs are required, the TRTD terminal board, which can accommodate two PRTD I/O packs, can be selected.
Core Functional Features
1. Eight Channels of Three-Wire RTD Input
The IS200SRTDH2A provides 8 fully independent three-wire RTD input channels. The three-wire connection method effectively compensates for lead wire resistance, ensuring measurement accuracy, and is a widely adopted standard in industrial temperature measurement. The board supplies a 10 mA DC multiplexed (not continuous) excitation current to each RTD, which can be installed grounded or ungrounded. The 8 RTDs can be located up to 300 meters (984 feet) from the turbine I/O cabinet, with a maximum total two-way cable resistance of 15 Ω.
2. Extensive RTD Type and Temperature Range Support
The IS200SRTDH2A, in conjunction with the PRTD I/O pack, supports a variety of standard RTD types, covering a wide measurement range from low to high temperatures. The supported RTD types include:
RTD Type | Name/Standard | Range °C | Range °F |
10 Ω Copper | MINCO_CA GE 10 Ω Copper | -51 to 260 | -60 to 500 |
100 Ω Platinum | SAMA 100 | -51 to 593 | -60 to 1100 |
100 Ω Platinum | DIN 43760 / IEC-751 / PT100_DIN | -51 to 700 | -60 to 1292 |
100 Ω Platinum | MINCO_PA / IPTS-68 / PT100_PURE | -51 to 700 | -60 to 1292 |
100 Ω Platinum | MINCO_PB / Rosemount 104 / PT100_USIND | -51 to 700 | -60 to 1292 |
120 Ω Nickel | MINCO_NA / N 120 | -51 to 249 | -60 to 480 |
200 Ω Platinum | PT 200 | -51 to 204 | -60 to 400 |
The full-scale input range for all RTD types is 0.3532 to 4.054 V (based on a 10 mA excitation current, corresponding to a resistance range of approximately 34 to 405 Ω). Linearization is performed by the processor in the PRTD I/O pack via software, ensuring high accuracy in temperature conversion.
3. Pluggable Terminal Design
The IS200SRTDH2A employs a right-angle header that accepts a variety of commercially available standard pluggable Euro-block terminal blocks, totaling 36 terminals. Compared to the fixed terminal version (SRTDH1), this pluggable design offers significant convenience: during field wiring, all cables can first be landed on the pluggable terminal block, which can then be inserted onto the board as a single unit for quick installation. When replacing the board, only the terminal block needs to be unplugged, eliminating the need to remove each wire individually and greatly reducing downtime for maintenance.
4. High-Precision Signal Conditioning and Noise Suppression
The IS200SRTDH2A board integrates noise suppression circuitry to effectively protect against surge and high-frequency noise interference. All RTD signals feature high-frequency decoupling to ground at the point of signal entry, ensuring signal integrity in industrial electromagnetic environments. The A/D converter in the PRTD I/O pack samples each signal and the excitation current using a time sample interval related to the power system frequency: 4 times per second (250 ms) for normal mode scanning, and 25 times per second (40 ms) for fast mode scanning. The A/D converter resolution is 14-bit, with AC common mode rejection of 60 dB at 50/60 Hz, DC common mode rejection of 80 dB, and normal mode rejection of up to 250 mV rms at 50/60 Hz system frequency with 60 dB for normal scan mode.
5. Automatic Calibration and Fault Detection
RTD inputs are automatically calibrated using filtered calibration source and null voltages, eliminating the need for on-site manual calibration. The IS200SRTDH2A, working with the PRTD I/O pack, provides multiple levels of fault detection:
Hardware Limit Checking: Each RTD type has preset (non-configurable) high and low hardware limits set near the ends of the operating range. If this limit is exceeded, a logic signal is set, and the corresponding input is removed from the scan sequence to prevent adverse effects on other input channels. Repaired channels are automatically reinstated into the scan within 20 seconds or can be manually reinstated.
System Limit Checking: Each RTD input has configurable high and low system limits that can be used to generate alarms, configurable for enable/disable and as latching/non-latching.
Open/Short Circuit Detection: RTD open and short circuits are detected through out-of-range values.
Board ID Chip Verification: An onboard read-only ID chip stores the terminal board's serial number, board type, revision number, and connector location. The PRTD I/O pack reads this information upon power-up initialization, and a hardware incompatibility fault is generated if a mismatch is detected.
6. Zero Configuration, Plug-and-Play
The IS200SRTDH2A is designed as a zero-configuration hardware device: the board has no jumpers or hardware setting switches and automatically enters the working state upon installation. All channel configuration, RTD type selection, sampling rate settings, alarm limits, and other parameters are performed by the PRTD I/O pack through the ToolboxST application software, significantly reducing installation and commissioning complexity.
Installation and Wiring Highlights
The IS200SRTDH2A supports two mounting methods: snapping onto a DIN-rail or direct flat mounting via mounting holes. During installation, the terminal board is first securely mounted. The PRTD I/O pack is then directly plugged into the DC-37 pin connector on the terminal board and mechanically secured using the threaded inserts adjacent to the Ethernet ports, in conjunction with a mounting bracket specific to the terminal board type. This ensures no right-angle force is applied to the connector.
For wiring, double-shielded cable must be used. All shields must be terminated at the shield terminal strip located adjacent to the terminal blocks; shields must not be grounded at the field device end. It is recommended to use #18 AWG (approximately 0.8 mm²) shielded twisted-pair wire. For the pluggable terminal blocks: insert the stripped wire ends into the corresponding holes of the terminal block and tighten the screws. After confirming the connections are secure, align the entire terminal block with the right-angle header on the board and push it into place to complete the electrical connection. During maintenance replacement, simply unplug the terminal block from the old board, install the new board, and plug the terminal block back in. No rewiring is needed.
Note that the IS200SRTDH2A supports only simplex operation. The PRTD I/O pack communicates with the controller via dual RJ-45 Ethernet ports (ENET1 and ENET2). If dual connections are used, the standard practice is to connect ENET1 to the network associated with the R controller. The I/O pack has inherent firmware soft-start capability, allowing its power connector to be plugged in while energized without needing to disconnect power first.
Accuracy Specifications
The table below lists the typical measurement accuracy at 400 °F (approx. 204 °C) for different RTD types. Accuracy is influenced by the selected gain group.
RTD Type | Group Gain | Accuracy at 400 °F |
120 Ω Nickel | 120 Ω Nickel | 2 °F (1.1 °C) |
200 Ω Platinum | Normal_1.0 | 2 °F (1.1 °C) |
100 Ω Platinum | Normal_1.0 | 4 °F (2.2 °C) |
100 Ω Platinum (-51 to 204 °C) | Gain_2.0 | 2 °F (1.1 °C) |
10 Ω Copper | 10 Ω Cu_10 | 10 °F (5.6 °C) |
Application Scenarios
The IS200SRTDH2A is suitable for various industrial process control applications requiring precise temperature monitoring. Typical applications include:
Monitoring of steam and gas turbine bearing and lubricant temperatures.
Monitoring of generator stator winding and core temperatures.
Monitoring of transformer winding and cooling system temperatures.
Monitoring of bearing temperatures for auxiliary equipment such as pumps and compressors.
Process pipeline media temperature measurement.
For any simplex control system requiring 8 or fewer RTD inputs, the IS200SRTDH2A, combined with the PRTD I/O pack, provides a compact, reliable, and high-precision temperature acquisition solution.
