The Allen-Bradley 1794-IT8 is an 8-channel thermocouple/millivolt input module for the FLEX I/O system, designed for direct interfacing with a wide variety of thermocouple sensors and low-level millivolt sources. The module includes cold-junction compensation and on-board scaling, simplifying programming and eliminating the need to scale data in the user program.
Item No :
1794-IT8Order(MOQ) :
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EXWProduct Origin :
Singapore/ChinaShipping Port :
WuhanLead Time :
3~5 daysWeight :
5kg| Specification | Description |
|---|---|
| Manufacturer | Rockwell Automation (Allen-Bradley) |
| Model | 1794-IT8 |
| Product Family | FLEX I/O |
| Product Type | Thermocouple / Millivolt Input Module |
| Input Channels | 8 |
| Nominal Input Range | ±76.5 mV |
| Resolution | 16 bits (2.384 µV typical) |
| Thermocouple Types | B, C, E, J, K, N, R, S, T, L |
| Accuracy (Fixed Digital Filter) | 0.025% of full scale + 0.5°C @ 24°C |
| Accuracy (No Filter) | 0.05% of full scale + 0.5°C @ 24°C |
| Normal Mode Noise Rejection | –60 dB @ 60 Hz |
| Common Mode Rejection | –115 dB @ 60 Hz; –100 dB @ 50 Hz |
| Channel Bandwidth | 0 to 2.62 Hz (–3 dB) default |
| System Throughput | 325 ms (1 channel scanned); programmable to 28 ms |
| FlexBus Current | 20 mA |
| Power Dissipation | 3 W max @ 31.2V DC |
| Isolation Voltage | 850 V DC |
| Keyswitch Position | 3 |
| Terminal Bases | 1794-TB2, -TB3, -TB3S, -TB3T, -TB3TS |
| Cold-Junction Compensator | 1794-CJC2 (2 shipped with new module) |
| Operating Temperature | 0°C to +55°C |
| Weight | Approx. 0.11–0.45 kg (varies by source) |
| Lifecycle Status | Discontinued / EOL – New Surplus available |
| Model | Description | Typical Application |
|---|---|---|
| 1794-IT8 (this model) | 8-ch thermocouple/mV input module, 16-bit | FLEX I/O temperature acquisition (discontinued) |
| 1794-IR8 | 8-ch RTD input module | RTD temperature measurement (companion module) |
| 1794-IRT8 | 8-ch thermocouple/RTD/mV input module | Mixed sensor temperature monitoring |
| 1794-IRT8XT | Extreme environment version of IRT8 | Harsh industrial environments |
| 5094-IT8 | Replacement module for 1794-IT8 | Migration path to FLEX 5000 platform |
| 1794-TB3T | Terminal base with CJC mounting | Required base for thermocouple mode |
| 1794-CJC2 | Cold-junction compensator | Required for thermocouple accuracy |
Q1: What is the primary function of the 1794-IT8?
It is an 8-channel thermocouple and millivolt input module for the FLEX I/O system. It accepts inputs from a variety of thermocouple types (B, C, E, J, K, N, R, S, T, L) and from millivolt sources in the ±76.5 mV range, converting them to digital data for the PLC controller .
Q2: What is the required keyswitch position for the 1794-IT8?
The keyswitch on the terminal base must be set to Position 3 before inserting the module. This position is required for safe mounting and operation of the thermocouple/mV module .
Q3: What is cold-junction compensation and why is it needed?
Cold-junction compensation (CJC) corrects for the voltage generated at the point where thermocouple wires connect to the terminal base, which would otherwise introduce errors in temperature readings. The 1794-IT8 uses 2 cold-junction compensators (1794-CJC2) mounted on the terminal base for channels 0–3 and 4–7 respectively .
Q4: Is the 1794-IT8 still in production?
No. The 1794-IT8 is discontinued (EOL) and is available only through aftermarket suppliers as New Surplus stock. Rockwell Automation recommends migrating to the FLEX 5000 platform (e.g., 5094-IT8) for new installations .
Q5: What are the common applications for the 1794-IT8?
It is widely used for temperature monitoring in process industries, including furnace/oven temperature control, boiler monitoring, heat treating, and any application requiring direct thermocouple interface to a PLC via FLEX I/O.
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