Allen-Bradley 1756-IT16 ControlLogix Input Module

1756-IT16 ControlLogix Non-Isolated Thermocouple/mV Input Module

1756-IT16 Product Introduction

The 1756-IT16 module from Allen-Bradley delivers high-density temperature measurement capabilities for your ControlLogix control system. This module offers 16 non-isolated analog input channels specifically designed for thermocouple and millivolt signal acquisition. It supports a wide range of thermocouple types including B, C, E, J, K, N, R, S, and T, making it incredibly versatile for various industrial temperature monitoring applications. With its 24-bit data resolution, the 1756-IT16 provides exceptional measurement accuracy and stability. The module requires two Cold Junction Compensation (CJC) sensors, sold separately as 1756-CJC, to deliver accurate temperature readings in thermocouple mode.

1756-IT16 Technical Specifications

The Allen-Bradley 1756-IT16 operates with an input range of -100 to 100 mV and provides 24-bit resolution for precise signal conversion. This module draws 200 mA from the 5.1V backplane and 80 mA from the 24V backplane. Its maximum power dissipation reaches 3W, translating to a thermal dissipation of 9.9 BTU/hour. The module provides 250V continuous isolation voltage and offers overvoltage protection up to +/-30V DC. For noise rejection, the 1756-IT16 achieves 75 dB at 60 Hz in normal mode, ensuring stable readings even in electrically noisy industrial environments. The operating temperature range spans 0°C to 60°C (32°F to 140°F), while storage temperatures can range from -40°C to 85°C. The module features an open-style enclosure and includes a status LED display for quick visual diagnostics.

Supported Thermocouple Types and Linearization

The 1756-IT16 supports an extensive array of thermocouple types to suit diverse temperature measurement needs. It accepts B, C, E, J, K, N, R, S, and T thermocouples, covering applications from cryogenic temperatures to high-temperature furnace monitoring. The module employs ITS-90 thermocouple linearization, which conforms to the internationally recognized temperature standard for maximum accuracy. For millivolt mode operation, you can directly connect DC millivolt sources such as strain gauges, pressure transducers, or other low-level signal generators. When operating in thermocouple mode, the Allen-Bradley 1756-IT16 relies on two CJC sensors to compensate for cold junction temperature variations. These sensors, specifically the 1756-CJC, mount directly to the module's RTB and measure the ambient temperature at the terminal block, enabling accurate thermocouple measurements regardless of environmental fluctuations.

Installation and Configuration

Installing the 1756-IT16 requires a standard slot in any 1756 ControlLogix chassis. You must mount the module directly into the chassis, ensuring proper alignment with the backplane connectors. For field wiring, you will need a compatible Removable Terminal Block (RTB) suitable for thermocouple connections. The module supports removal and insertion under power (RIUP), simplifying maintenance without interrupting system operation. Before installation, ensure you have properly installed and grounded the chassis and power supply. When connecting thermocouples, use appropriate extension wire matching the thermocouple type to maintain measurement accuracy. For best results, keep thermocouple leads as short as possible and avoid routing them alongside high-power AC cables. The 1756-IT16 also requires you to install two 1756-CJC sensors on the RTB for accurate cold junction compensation. These sensors measure the temperature at the terminal block, allowing the module to correct for thermal errors introduced at the connection point.

Application Scenarios

The Allen-Bradley 1756-IT16 finds widespread use across industries requiring precise temperature monitoring. Common applications include furnace and kiln temperature control in metal processing and ceramics manufacturing. In the chemical and petrochemical sectors, the module monitors reactor temperatures, distillation columns, and pipeline temperatures. Food and beverage processors use the 1756-IT16 for pasteurization, sterilization, and cooking temperature control. Pharmaceutical manufacturers rely on it for fermentation monitoring and environmental chamber control. The module also serves in power generation for boiler and turbine temperature monitoring. For millivolt mode applications, the 1756-IT16 connects to strain gauges for structural monitoring, load cells for weight measurement, and pressure transducers for hydraulic system monitoring. Its 16-channel high-density design makes it particularly suitable for applications with multiple temperature zones or large numbers of sensing points, reducing the total number of modules required and conserving chassis slots.

Packaging and Shipping

Each 1756-IT16 module ships in anti-static protective packaging to safeguard against electrostatic discharge. We thoroughly inspect every unit before shipment to guarantee full functionality and performance. The package contains the module only. Please note that the 1756-CJC cold junction compensation sensors are not included and require separate purchase. Additionally, the RTB housing is not included and must be ordered separately. We ship worldwide using FedEx, UPS, or DHL, processing all orders within 24 hours. Upon dispatch, you will receive a tracking number to monitor your shipment's progress.

Frequently Asked Questions

Q: What thermocouple types does the 1756-IT16 support?
A: The Allen-Bradley 1756-IT16 supports B, C, E, J, K, N, R, S, and T thermocouple types. It also accepts millivolt signals in the range of -100 to 100 mV, making it versatile for various temperature and low-level voltage measurement applications.

Q: Are the CJC sensors included with the 1756-IT16 module?
A: No, the two required CJC sensors are not included with the 1756-IT16. You must purchase them separately using part number 1756-CJC. These sensors mount on the RTB and provide essential cold junction compensation for accurate thermocouple measurements.

Q: What is the resolution of the 1756-IT16 module?
A: The 1756-IT16 provides 24-bit data resolution, delivering exceptional measurement precision and sensitivity for thermocouple and millivolt signals. This high resolution ensures accurate temperature readings across the entire measurement range.

Q: Can the 1756-IT16 be replaced while the system is powered?
A: Yes, the Allen-Bradley 1756-IT16 supports removal and insertion under power (RIUP). This capability allows you to replace or install the module without shutting down the entire ControlLogix chassis, minimizing production downtime during maintenance.

Q: What is the purpose of the two CJC sensors on the 1756-IT16?
A: The two 1756-CJC sensors measure the temperature at the terminal block where thermocouples connect to the 1756-IT16. The module uses this information to compensate for the cold junction temperature, ensuring accurate thermocouple readings regardless of ambient temperature variations in the control cabinet.