Product Overview for the 1746-ITB16 Fast Response Input Module

The 1746-ITB16 is a fast response discrete input module for the SLC 500 platform. Firstly, this module is manufactured by Rockwell Automation under the Allen-Bradley brand. Specifically, the 1746-ITB16 features sixteen (16) input channels in a single group. In addition, this module accepts a nominal input voltage of 24V DC with a 10-30V DC range. The wiring configuration is sinking type for standard industrial sensors. Consequently, the 1746-ITB16 is designed to receive high-speed inputs or signals that operate at rapid switching frequencies. Therefore, this module is ideal for time-critical applications such as high-speed counting and encoder monitoring.

Fast Response Performance

High-Speed Input Capability
The 1746-ITB16 delivers exceptional speed for discrete inputs. Firstly, the maximum signal delay for the ON state (OFF to ON) is only 0.3 milliseconds. In addition, the maximum signal delay for the OFF state (ON to OFF) is 0.5 milliseconds. Specifically, these fast response times capture short-duration events that standard input modules would miss. Consequently, the 1746-ITB16 suits applications such as high-speed packaging, assembly machines, and motion control systems.

Frequency Reading Capability
The 1746-ITB16 reads high-frequency pulses when used with appropriate processors. Firstly, when used with SLC 5/03 or SLC 5/04 processors, discrete input interrupt (DII) instructions with 100 microsecond polling can read up to 1 kHz frequency pulses. In addition, if signals originate from a gray code encoder, the pulse frequency can reach up to 2 kHz. Specifically, the recommended Allen-Bradley device for gray code applications is the 845D Absolute Gray Code Encoder. Consequently, the 1746-ITB16 supports precise position and speed monitoring.

Input Channel Configuration

Sixteen Sinking Input Channels
The 1746-ITB16 offers sixteen sinking input channels in one group. Firstly, sinking wiring means the input provides a path to DC common when active. In addition, this configuration is standard for most DC proximity sensors and photoelectric sensors. Specifically, all sixteen channels share a single common terminal for simplified wiring. Consequently, the 1746-ITB16 reduces wiring complexity compared to multiple smaller modules. Therefore, panel space and installation time are both minimized.

Voltage and Current Specifications
The 1746-ITB16 operates within standard industrial DC ranges. Firstly, the nominal input voltage is 24V DC for compatibility with common power supplies. In addition, the input voltage range is 10 to 30V DC for tolerance of voltage variations. Specifically, the nominal input current is 8 mA at 24V DC for low power consumption. The maximum off-state voltage is 5V DC, and the maximum off-state current is 1.5 mA. Consequently, the 1746-ITB16 presents a light load to field sensors and power supplies.

Power Consumption and Heat Dissipation

Low Backplane Current Draw
The 1746-ITB16 consumes minimal power from the SLC 500 chassis. Firstly, the backplane current at 5V DC is only 85 milliamps (0.085 A). In addition, this low consumption leaves ample power budget for other modules in the chassis. Specifically, the module does not draw any current from the 24V DC backplane supply. Consequently, the 1746-ITB16 does not significantly impact the overall system power requirements. Therefore, you can install many input modules without exceeding chassis power limits.

Maximum Power Dissipation
The 1746-ITB16 dissipates minimal heat during operation. Firstly, the maximum power dissipation is 3.6 Watts for the entire module. In addition, this low dissipation reduces cooling requirements within the control cabinet. Specifically, the module remains cool even in high-density chassis configurations. Consequently, the 1746-ITB16 contributes little to overall cabinet temperature rise. Therefore, you can install this module in sealed enclosures without active cooling.

Installation and Compatibility

Single Slot Occupancy
The 1746-ITB16 occupies only one slot in the SLC 500 chassis. Firstly, the module installs directly into any available slot of the 1746 chassis. In addition, it is compatible with any SLC 500 processor, including fixed and modular styles. Specifically, the module attaches directly to the chassis backplane for power and communication. Consequently, the 1746-ITB16 maximizes I/O density in space-constrained applications.

RIUP Restriction
The 1746-ITB16 does not support removal under power (RIUP). Firstly, you must remove power from the chassis before installing or removing this module. In addition, installing or removing the module under power may cause damage or unpredictable operation. Specifically, always disconnect the SLC 500 system power before handling the 1746-ITB16. Consequently, follow proper lockout/tagout procedures before module installation.

Troubleshooting and Diagnostics

LED Status Indicators
The 1746-ITB16 includes LED indicators for each input channel. Firstly, LEDs show the ON or OFF status of all sixteen input points. In addition, these indicators provide immediate visual feedback without test equipment. Specifically, a lit LED indicates that the input is receiving a valid ON signal. Consequently, technicians can quickly identify active field devices during troubleshooting. Therefore, the 1746-ITB16 reduces maintenance time and improves diagnostic efficiency.

Optical Isolation for Noise Immunity
The 1746-ITB16 includes filter circuitry and optical coupling. Firstly, this design reduces signal noise from electrical interference. In addition, optical coupling isolates the field inputs from the backplane logic. Specifically, the filter circuitry removes high-frequency noise that could cause false triggering. Consequently, the 1746-ITB16 delivers reliable input readings even in electrically noisy industrial environments.

Technical Specifications of the 1746-ITB16

General Specifications

• Manufacturer: Rockwell Automation.

• Brand: Allen-Bradley.

• Part Number / Catalog No.: 1746-ITB16.

• Series: SLC 500.

• Module Type: Fast response discrete input module.

• Applications: Combination 120 Volts AC I/O, high-speed inputs.

• UPC: 10662468070529.

Input Channel Specifications

• Number of Inputs: Sixteen (16).

• Number of Groups: One (1) group of 16 channels.

• Wiring Configuration: Sink wiring configuration.

Voltage Specifications

• Nominal Input Voltage: 24V DC.

• Input Voltage Range: 10 to 30 V DC.

• Maximum Off-State Voltage: 5V DC.

Current Specifications

• Nominal Input Current: 8 mA at 24V DC.

• Maximum Off-State Current: 1.5 mA.

Response Time Specifications

• Maximum Signal Delay (ON - OFF to ON): 0.3 ms.

• Maximum Signal Delay (OFF - ON to OFF): 0.5 ms.

Power Specifications

• Backplane Current (5 Volts DC): 85 milliamps (0.085 A).

• Maximum Power Dissipation: 3.6 W.

High-Speed Capabilities (with SLC 5/03 or 5/04)

• DII Polling: 100 µsec.

• Frequency Pulse Reading (Standard): Up to 1 kHz.

• Frequency Pulse Reading (Gray Code Encoder): Up to 2 kHz.

• Recommended Gray Code Encoder: 845D Absolute Gray Code Encoder.

Environmental Specifications

• Operating Temperature: 32 to 140°F (0 to 60°C).

• Relative Humidity: 5% to 95% non-condensing.

Installation Guide for the 1746-ITB16

Follow these steps for a proper installation of the 1746-ITB16.

Step 1: Power Disconnection
Firstly, disconnect all power from the SLC 500 chassis before installation. The 1746-ITB16 does not support removal under power (RIUP). Then, verify that no voltage is present on any conductor. Consequently, module damage and personal injury will be prevented.

Step 2: Slot Selection
After that, select any available slot in your SLC 500 chassis for the 1746-ITB16. This module is compatible with any SLC 500 processor. Then, ensure the slot is clean and free of debris.

Step 3: Module Installation
Then, insert the 1746-ITB16 into the chosen slot. Align the module with the card guides on the top and bottom. Push firmly until the module seats completely in the backplane connector. Secure the module using the retaining screws at the top and bottom.

Step 4: Field Device Wiring
Furthermore, connect your sinking field devices to the 1746-ITB16 input terminals. For sinking configuration, connect the sensor output to the input terminal. Connect the sensor common to the DC common terminal. The nominal input voltage is 24V DC with a range of 10 to 30V DC.

Step 5: Power Up and Testing
Finally, apply power to the SLC 500 system. Observe the LED indicators on the 1746-ITB16 for each input channel. Activate each field device and verify the corresponding LED illuminates within 0.3 ms. For high-speed applications, verify that the processor captures all input transitions correctly.

Packaging List for the 1746-ITB16

• 1746-ITB16 Fast Response Discrete Input Module (1 unit)

• Product documentation and installation guide (1 copy)

Frequently Asked Questions (FAQs) About the 1746-ITB16

Q1: How many input channels does the 1746-ITB16 provide?

The 1746-ITB16 provides sixteen (16) discrete input channels. All channels are in a single group with one common terminal. Therefore, one module monitors up to 16 high-speed field devices.

Q2: What is the response time of the 1746-ITB16?

The 1746-ITB16 has a maximum ON delay (OFF to ON) of 0.3 milliseconds. The maximum OFF delay (ON to OFF) is 0.5 milliseconds. Therefore, this module captures very fast input signals that standard modules would miss.

Q3: What is the difference between sinking and sourcing inputs on the 1746-ITB16?

The 1746-ITB16 is a sinking input module. Sinking means the input provides a path to DC common when active. Therefore, connect sensors that source (provide) positive voltage to the input terminals.

Q4: Does the 1746-ITB16 support removal under power (RIUP)?

No, it does not. The 1746-ITB16 does not support removal under power. Therefore, you must disconnect power from the SLC 500 chassis before installing or removing this module.

Q5: What is the maximum frequency the 1746-ITB16 can read?

When used with SLC 5/03 or SLC 5/04 processors, the 1746-ITB16 reads up to 1 kHz standard pulses. For gray code encoder signals, it reads up to 2 kHz. Therefore, this module supports high-speed counting and position monitoring applications.