Why Discrete DC Sensing Stalls Your Line
A stalled input card stops the whole ControlLogix chassis from seeing field status. When a digital DC input module fails or cannot be sourced quickly, commissioning windows close and production waits. The Allen-Bradley 1756-IB16/A answers that problem directly: a ControlLogix 16-point digital DC input module built for low-voltage discrete DC sensing, available as a ready-to-ship spare from Oil AutoTech.
This module belongs to the Bulletin 1756 ControlLogix family. It carries 16 inputs arranged in two groups of eight, so one card covers a dense block of field devices without expanding the rack.
What the 1756-IB16/A Delivers
Input Capacity and Grouping
Sixteen points split into 8 per group let you separate field circuits cleanly. That grouping matters when one machine section needs isolation from another, and it keeps troubleshooting contained to a single group instead of the entire card.
Wide DC Input Range
The module accepts 10-31.2 V DC. That window covers common industrial DC control levels and tolerates the supply variation found on real plant floors, so nuisance input dropouts become far less likely.
Configurable Input Filter
Filter time is configurable from 0 to 18 ms. Short filter settings suit fast machine events; longer settings reject contact bounce and electrical noise. You tune the response to the application rather than accepting a fixed compromise.
Isolation and Backplane Load
The card provides 250 V continuous isolation. It draws 100 mA at 5.1 V and 2 mA at 24 V from the backplane, a light load that leaves headroom for other modules in the chassis.
Environmental Range
Operation is rated from 0 to 60 C, matching the ControlLogix family specification for standard control cabinets.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 1756-IB16/A |
| Manufacturer | Allen-Bradley (Rockwell Automation) |
| Series | ControlLogix / Bulletin 1756 |
| Product Type | Digital DC Input Module |
| Inputs | 16, arranged 8 per group |
| Input Voltage Range | 10-31.2 V DC |
| Configurable Filter | 0-18 ms |
| Isolation | 250 V |
| Backplane Current | 100 mA at 5.1 V / 2 mA at 24 V |
| Operating Temperature | 0 to 60 C |
| Terminal Blocks | 1756-TBNH or 1756-TBSH (removable) |
| Lifecycle Status | Active |
Where This Module Earns Its Place
Oil and Gas Skids
Pump and valve status signals arrive as discrete DC contacts. The 10-31.2 V DC range and 250 V isolation handle the electrical environment of a skid panel, while the 8-per-group layout keeps each skid section on its own input group.
Packaging and Material Handling
Photo-eyes, limit switches and proximity sensors fire quickly. A short filter setting keeps those events visible to the controller, and the 16-point density reduces the number of cards needed per line.
Panel Builders Replacing a Failed Card
When an existing input card drops out mid-shift, the practical question is availability. Oil AutoTech supplies fast-dispatch spares for oil, gas and industrial automation, so a replacement 1756-IB16/A can be on its way without a long sourcing cycle.
Installation and Setup
Mount the module in any slot of a 1756 ControlLogix chassis; the backplane handles communication between modules. Wire field devices to the removable terminal block, using either the 1756-TBNH or 1756-TBSH style. Configure the module in Studio 5000 Logix Designer, where you also set the input filter time. Confirm your field supply sits inside the 10-31.2 V DC window before energizing, and verify group assignment so each eight-point block matches your drawing.
Compatibility and Integration
This module is programmed and configured in Studio 5000 Logix Designer (formerly RSLogix 5000). Chassis-based communication modules in the same rack support EtherNet/IP, ControlNet, DeviceNet and DH+/Remote I/O, so the card fits existing ControlLogix architectures without a redesign.
Integration Note
Wiring into these networks may require an external gateway or connection module depending on your existing architecture. Confirm cables and gateways with your supplier before ordering.
Maintenance and Reliability
Inspect terminal block connections periodically and keep the cabinet within the 0 to 60 C operating range. Because the module is solid-state with no moving parts, the main wear points sit outside the card: field wiring, terminal block seating and cabinet cooling. Log filter settings during commissioning so future troubleshooting starts from a known baseline. Keeping one spare on the shelf shortens any unplanned stop.
Selection Checklist
Before ordering, confirm your field voltage falls within 10-31.2 V DC, count the discrete points you need, and check whether your wiring suits the 1756-TBNH or 1756-TBSH terminal block. Verify the chassis has a dedicated 1756 power supply module and sufficient backplane capacity. Oil AutoTech offers hands-on technical selection help, so you can match the card to your application before it ships.
Frequently Asked Questions
How many inputs does the 1756-IB16/A provide?
It provides 16 inputs arranged in two groups of 8.
What input voltage range does this module accept?
The module accepts 10-31.2 V DC.
Can I adjust the input filter time?
Yes. Filter time is configurable from 0 to 18 ms in Studio 5000 Logix Designer.
Which terminal blocks does it use?
It uses 1756-TBNH or 1756-TBSH removable terminal blocks.
Is this module still available?
Yes. The 1756-IB16/A is an active product. Contact Oil AutoTech today for pricing and availability.
