The Allen-Bradley 1756-IC16/A, also cataloged as the 1756-IC16 DC Input Module, accepts 48 VDC sinking input signals through 16 channels and transfers their status to the ControlLogix backplane. Rockwell Automation specifies a 30-60 VDC input module with 8 points per group.

Model Reference

The 1756-IC16 is a ControlLogix digital input module rated for 48 VDC nominal operation. Its 16 inputs are arranged as two groups of 8 points. The module provides status indication through front-panel LEDs and uses a 20-pin removable terminal block interface.

The supplied spare references are 1756IC16 and 1756-IC16/A. The current Rockwell Automation product page identifies the catalog number 1756-IC16 and lists it as an active ControlLogix product.

Hardware Specifications

The operating-voltage limits, input-current thresholds, backplane current, power dissipation, filtering, update time, and isolation values above are taken from Rockwell Automation technical data.

Backplane Communication and I/O Behavior

The 1756-IC16 converts the electrical state of each 48 VDC input into status data transferred through the ControlLogix backplane. The module provides 16 discrete input points divided into two groups of eight.

Input transition timing is selectable through software filtering. The specified hardware delay is up to 1 ms for off-to-on transitions and up to 4 ms for on-to-off transitions, before the selected filter interval is added.

The module supports software-configurable change-of-state operation and input timestamps with a specified accuracy of +/-200 us. These functions allow controller logic to process input transitions without relying only on periodic state polling.

Industrial Control Characteristics

The 1756-IC16 uses a sinking 48 VDC input architecture. The minimum specified on-state current is 2 mA at 30 VDC, while the maximum specified operating current is 7 mA at 60 VDC. The specified maximum off-state current is 1.5 mA.

Isolation is provided between the input system and the backplane at 250 V continuous, with 125 V continuous isolation between the two input groups. Individual inputs within the same group are not isolated from each other.

The module draws 100 mA from the 5.1 VDC backplane supply and 3 mA from the 24 VDC backplane supply. Total backplane power is 0.58 W, while maximum module power dissipation is 5.2 W at 60 deg C.

Ordering Information

• 1 x Allen-Bradley 1756-IC16 ControlLogix 16 Point 48 VDC Digital Input Module
• 1 x 1756-IC16 module assembly
• 1 x Compatible removable terminal block selected separately as required, such as 1756-TBNH or 1756-TBSH
• 1 x Suitable ControlLogix chassis position is required for installation
• Field wiring, prewired cables, and interface modules are separate components unless specifically included in the configuration

Installation and Wiring Guidelines

Input wiring

• Verify that the field source is compatible with the 48 VDC sinking input architecture.
• Keep the applied input voltage within the published operating range.
• Confirm polarity before energizing field circuits.
• Separate DC control wiring from high-current switching conductors where practical.

Terminal connections

• Use the specified removable terminal block type for the installation.
• Follow the ControlLogix wiring documentation for terminal assignment and conductor preparation.
• Ensure each conductor is mechanically secured before applying field voltage.

Grouping and isolation

• Treat the two eight-point input groups according to the specified group isolation arrangement.
• Do not assume that individual inputs within one group are galvanically isolated.
• Use an appropriately isolated interface when independent channel isolation is required.

Filtering and signal integrity

• Select the input filter interval according to the required transition response.
• Avoid excessive filtering for signals where short pulses must be detected.
• Avoid routing input conductors adjacent to high-energy switching cables where electrical interference is possible.

Frequently Asked Questions

• How many inputs are provided by the 1756-IC16?
  The module has 16 DC inputs arranged as two groups of 8 points. The input voltage category is 48 VDC sink.
• What voltage does the 1756-IC16 require?
  Its nominal input voltage is 48 VDC. The specified operating range is 30-60 VDC, with a reduced upper limit at elevated temperature.
• What is the maximum off-state current?
  The specified maximum off-state input current is 1.5 mA. The maximum off-state voltage is 10 VDC.
• What current is required to turn an input on?
  The minimum specified on-state current is 2 mA at 30 VDC, while the maximum operating current is 7 mA at 60 VDC.
• Are all 16 inputs individually isolated?
  No. Inputs are grouped in two sets of eight. Group-to-group isolation is specified at 125 V continuous, but inputs within a group are not individually isolated.
• What is the ControlLogix backplane current draw?
  The module draws 100 mA at 5.1 VDC and 3 mA at 24 VDC. Total backplane power is specified as 0.58 W.
• Can the input filter time be configured?
  Yes. Software-selectable filtering is provided. The documented filter selections include 0 ms, 1 ms, 2 ms, 9 ms, and 18 ms as applicable to input transition timing.
• Which terminal blocks are compatible?
  Rockwell Automation lists 1756-TBNH and 1756-TBSH removable terminal blocks for the 1756-IC16. The module occupies one ControlLogix chassis slot.