PLC 1794-IT8 Thermocouple Input Module

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Location: 3203 Guomao Building, No.388, Hubin south Road, Siming district, Xiamen,Fujian,China

Description:1794-IT8

The 1794-IT8 is a FLEX I/O module designed to interface with a wide range of thermocouples and millivolt-level signals. It provides 8 independent input channels, converting analog temperature or voltage signals into digital data for communication with a programmable controller. This module is ideal for distributed I/O applications requiring cost-effective temperature monitoring without the need for high-speed response or extreme precision. It supports both grounded and ungrounded thermocouples when proper installation guidelines are followed. Communication is typically handled through block transfer reads/writes via the FLEX I/O adapter.

Parameters:1794-IT8

Product Line: FLEX I/O
Product Type: Thermocouple / Millivolt Input Module
Number of Inputs:8 Channels
Millivolt Range:±76.5 mV
Resolution:16 bits (2.384 µV typical)
Data Format:16-bit 2’s complement or offset binary (unipolar)
Power Supply:24V DC
FlexBus Current Draw:20 mA
Power Dissipation:3 W maximum @ 31.2V DC
Isolation Voltage:Tested at 850V DC for 1 second (between inputs/user power and logic)
Normal Mode Noise Rejection:-60 dB at 60 Hz
Channel Bandwidth:0 to 2.62 Hz (-3 dB)

FAQ:1794-IT8

Q1: What type of sensors can I connect to the 1794-IT8?
A: The module supports a wide range of thermocouple types, including J, K, E, R, N, S, B, C, T, and L. It also accepts a direct millivolt input signal in the range of ±76.5 mV .

Q2: What is the purpose of the Cold Junction Compensator (CJC)?
A: The CJC assembly is required for accurate thermocouple readings. It measures the temperature at the terminal block connection point, allowing the module to compensate for the voltage generated where the thermocouple wire meets the copper terminals. Two compensators are included with the module, and they mount on the 1794-TB3T terminal base.

Q3: What happens if I select an invalid thermocouple type during configuration?
A: If an invalid thermocouple type is selected, the module will set the "Bad Structure" diagnostic bit (Read Word 10/11, Bit 02). This indicates a configuration error that prevents proper operation until corrected.