1734-IT2I New Factory I/O Point Input Module 1734IT2I
PRODUCT DETAILS
1734-IT2I — POINT I/O 2-Channel Isolated Thermocouple Input Module
The 1734-IT2I is a two-channel thermocouple input module for the 1734 POINT I/O platform. Both channels accept standard thermocouple types (J, K, T, E, R, S, B) and report calibrated temperature readings in degrees Celsius or Fahrenheit directly to the controller, with built-in cold junction compensation handled on the module. The "I" suffix means the channels are individually isolated from each other and from the POINT I/O backplane — neither channel shares a reference with the other or with the control system ground.
Two channels is often exactly the right count for localized temperature monitoring at a POINT I/O node — one process thermocouple and one reference or safety thermocouple, a motor winding and bearing temperature pair, or inlet and outlet temperatures on a heat exchanger section. The individual channel isolation makes it straightforward to connect thermocouples from physically separate equipment with different ground references without creating measurement errors from ground loops.
Specifications
| Parameter | Value |
|---|---|
| Part Number | 1734-IT2I |
| Platform | POINT I/O (1734) |
| Input Channels | 2 (individually isolated) |
| Thermocouple Types | J, K, T, E, R, S, B |
| Temperature Range (Type K) | −200°C to +1370°C |
| Temperature Range (Type J) | −210°C to +760°C |
| Temperature Range (Type T) | −200°C to +400°C |
| Resolution | 0.1°C |
| Accuracy | ±1°C typical @ 25°C ambient |
| Cold Junction Compensation | Internal, automatic |
| Channel Isolation | Channel-to-channel and channel-to-backplane |
| Isolation Voltage | 250V AC continuous |
| Open-Circuit Detection | Yes (upscale or downscale configurable) |
| Backplane Current (5V) | 100 mA |
| Operating Temperature | −20°C to 55°C |
| Standards | UL 508, CE, IEC 61131-2 |
Thermocouple Types and Accuracy
The module supports seven IEC standard thermocouple types. Selecting the right type for an application depends on temperature range, accuracy requirements, and the environment:
- Type K (Chromel/Alumel) — the most versatile general-purpose choice. Wide range (up to 1370°C), good linearity across mid-range temperatures, and widely available. Used in furnaces, industrial ovens, and general process temperature measurement.
- Type J (Iron/Constantan) — common in older equipment and food processing applications. Lower maximum temperature than K, but slightly better sensitivity in the 0–400°C range. Avoid in humid environments — the iron conductor corrodes.
- Type T (Copper/Constantan) — the best choice for cryogenic and sub-zero applications. Accurate and stable below 0°C where K and J performance degrades. Common in refrigeration, cold storage, and laboratory systems.
- Types R, S (Platinum/Rhodium) — high-accuracy, high-temperature types for metallurgical and glass furnace applications. Expensive and fragile; only justified where the temperature range or accuracy requirement demands them.
- Type B — extreme temperatures up to 1820°C. Used in the most demanding high-temperature industrial processes.
The module's ±1°C typical accuracy applies to the signal conditioning and cold junction compensation electronics. The overall system accuracy also depends on the thermocouple's own calibration tolerance — standard tolerances for Type K are ±2.2°C or ±0.75%, whichever is greater. For critical measurements, use Special Limits of Error (SLE) thermocouples which offer ±1.1°C or ±0.4%.
FAQ
Q: Can the module detect a broken or disconnected thermocouple?
Yes. Open-circuit detection is built in. When a thermocouple wire breaks or disconnects, the channel drives to either full upscale or full downscale (configurable in the module properties). The controller program can monitor for this out-of-range condition to trigger an alarm.
Q: Can the two channels measure different thermocouple types simultaneously?
Yes. Each channel is configured independently in Studio 5000 — channel 0 can be Type K while channel 1 is Type T, or any other combination from the supported types.
Q: How long can the thermocouple extension wire be between the junction and the module?
Thermocouple extension wire must be used — not standard copper wire — to avoid introducing additional thermoelectric junctions that generate spurious voltages. Extension wire runs of 30–60 m are common without significant accuracy degradation, provided the wire is properly shielded and routed away from noise sources. Use the correct extension wire type for the thermocouple type (Type K extension wire for Type K thermocouples, etc.).
Q: What POINT I/O adapters is the 1734-IT2I compatible with?
All standard 1734 adapters are compatible — EtherNet/IP (1734-AENT), DeviceNet (1734-ADN), ControlNet (1734-ACN), and others. The thermocouple module communicates via the POINT I/O backplane and is independent of network protocol.
Q: The accuracy spec is ±1°C — does that apply across the full temperature range?
The ±1°C figure is the module electronics accuracy at 25°C ambient. At extreme temperatures (near the top of a thermocouple's range) and at ambient temperatures away from 25°C, total system accuracy is higher due to the thermocouple's own non-linearity and the temperature coefficient of the module's electronics. For applications requiring tighter accuracy at specific temperature ranges, check the full accuracy specification across the operating temperature and input range.