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Brand: Allen-Bradley
Allen-Bradley 1756-IB16D ControlLogix Diagnostic DC Input
Description
Diagnostic 24 V DC inputs with field-fault reporting
The Allen-Bradley 1756-IB16D is a 16-point diagnostic DC input module. It uses the same 12/24 V DC sinking input category as the standard 1756-IB16 but groups the points in fours and adds diagnostics, so the controller can tell a broken wire from a genuinely open contact: the data lists open-wire detection that relies on a minimum off-state leakage current of 1.2 mA, with diagnostics time-stamped to plus or minus 1 ms. That information is valuable for safety-related interlocks and for remote sites where nobody walks the cabinets daily.
The Rockwell product page describes it as a 10 to 30 V DC diagnostic input with 16 points, and it uses the 36-pin 1756-TBCH removable terminal block rather than the TBNH style used by the plain IB16.
Technical specifications
| Parameter | Specification |
|---|---|
| Catalog number | 1756-IB16D (1756-IB16DK conformal coated listed separately) |
| Inputs | 16 diagnostic, 4 points per group |
| Voltage category | 12/24 V DC sink |
| Operating voltage range | 10 to 30 V DC; nominal 24 V DC |
| Off-state voltage / current, max | 5 V / 1.5 mA |
| On-state current | 2 mA min at 10 V DC; 13 mA max at 30 V DC |
| Input impedance, max | 2.31 kOhm at 30 V DC |
| Input delay, off to on | 340 us nominal / 1 ms max plus filter (0, 1 or 2 ms) |
| Input delay, on to off | 740 us nominal / 4 ms max plus filter (0, 1, 9 or 18 ms) |
| Cyclic update time | 200 us to 750 ms; time stamp +/-200 us |
| Backplane current | 150 mA at 5.1 V DC; 3 mA at 24 V DC (0.84 W) |
| Power dissipation, max | 5.8 W at 60 C (19.78 BTU/hr) |
| Isolation | 250 V continuous basic, input to backplane and group to group |
| Terminal block | 1756-TBCH (ordered separately) |
| Reverse polarity protection | Yes |
| Temperature code | T3 |
| Operating temperature | 0 to +60 C |
| Non-operating temperature | -40 to +85 C |
| Vibration / shock | 2 g at 10-500 Hz / 30 g operating, 50 g non-operating |
| Slot width / keying | 1 slot; electronic keying, software configurable |
| Enclosure / wire category | Open-style; wire category 1 |
Where diagnostics pay off
The four-point groups let one field supply feed a small cluster of devices, and each group can be wired and checked as a unit. Compared with the plain IB16, this module draws 150 mA from the 5.1 V rail and dissipates up to 5.8 W, so the chassis power budget should be re-checked when many diagnostic cards replace standard ones. The inrush limit of 250 mA applies at power-up of each field circuit.
Selection points
Choose the IB16D when the application needs field-fault visibility, otherwise the cheaper IB16 covers ordinary switch and sensor duty. Use the higher on-state current of 13 mA at 30 V in your loop calculations, and plan for the TBCH terminal block, which is a separate item. Confirm the exact suffix and series before you order; the open-wire function needs the field device or a parallel resistor to pass at least 1.2 mA when off.
Documents and quotation
The linked Rockwell Automation technical data covers the full 1756 I/O range (file size about 15 MB, hosted by Rockwell Automation). Related PLC hardware sits in the PLC & I/O Cards category. To request a price send your catalog number and quantity to Seven Star LLC, an independent supplier based in Muscat.
Datasheets & Documents
- Technical data Rockwell Automation 1756 ControlLogix I/O Specifications, publication 1756-TD002U (September 2026) Download
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About brand
Allen-Bradley is the brand of Rockwell Automation for industrial control: ControlLogix and CompactLogix controllers, I/O systems, PanelView operator terminals, PowerFlex drives, motor control and industrial network equipment. The company began in Milwaukee in 1903, when Lynde Bradley and Dr. Stanton Allen formed the Compression Rheostat Company to make the motor speed controller Bradley had invented in 1901. It took the name Allen-Bradley in 1909 and was bought by Rockwell International in 1985. Since 2001 its owner has been Rockwell Automation, which is still headquartered in Milwaukee, Wisconsin.
Allen-Bradley company profile
| Founded | 1903, Milwaukee, Wisconsin, USA, as the Compression Rheostat Company |
|---|---|
| Founders | Lynde Bradley (inventor of the compression rheostat, 1901) and Dr. Stanton Allen (investor); Harry Bradley joined in 1904 |
| Name | Allen-Bradley Company from 1909 |
| Ownership | Acquired by Rockwell International in 1985 for about USD 1.65 billion; a brand of Rockwell Automation (NYSE: ROK) since 2001 |
| Headquarters | Milwaukee, Wisconsin, USA |
| Product families | Logix programmable automation controllers (ControlLogix, CompactLogix), legacy SLC 500 and MicroLogix PLCs, Micro800 controllers, POINT, FLEX and Compact I/O, PanelView HMIs, PowerFlex AC drives, contactors, motor starters and soft starters, safety components, Stratix Ethernet switches |
Milestones
- 1901: Lynde Bradley invents the compression rheostat to control the speed of electric motors.
- 1903: The Compression Rheostat Company is formed in Milwaukee with an initial investment of USD 1,000.
- 1904: Harry Bradley joins; a crane controller is shown at the St. Louis World's Fair.
- 1909: The company is renamed Allen-Bradley.
- 1985: Rockwell International acquires Allen-Bradley.
- 2001: Rockwell Automation becomes the company's name; the Allen-Bradley brand marks 100 years in 2003.
Reading Allen-Bradley catalogue numbers
The first digits of an Allen-Bradley catalogue number identify the platform, which tells you what is compatible with what. 1756 is ControlLogix (chassis-based, used for large process and plant control), 1769 is CompactLogix 5370 with Compact I/O, 5069 is CompactLogix 5380 with Compact 5000 I/O, 1734 is POINT I/O, 1794 and 5094 are FLEX and FLEX 5000 distributed I/O, 1746 and 1747 belong to the older SLC 500 family, 1766 is MicroLogix 1400 and 2080 is Micro800. For drives, 25B is PowerFlex 525 and 22B is PowerFlex 40; in a code such as 25B-D010N114, "D" means 380–480 V, "010" is the output current rating, and N114 instead of N104 means the drive has an integrated EMC filter. Many plants in the region still run SLC 500 and older MicroLogix systems, which Rockwell has discontinued, so exact spares and migration to CompactLogix are both common requests.
Where Allen-Bradley products are used
In Oman and the GCC, Allen-Bradley controllers and drives run on oil and gas facilities, water treatment and pumping stations, cement, food and beverage and packaging plants, and on machines supplied by American OEMs. ControlLogix is often the platform for plant control systems, while PowerFlex drives are used on pumps, fans and conveyors.
Allen-Bradley products we list
| Family | Examples |
|---|---|
| ControlLogix | 1756-L85E, 1756-EN2T, 1756-EN2TR, 1756-IF16, 1756-IB32, 1756-PA75, 1756-A10 |
| CompactLogix and Micro controllers | 5069-L320ER, 5069-L340ERM, 1769-L33ER, 1769-L16ER, MicroLogix 1400, Micro820, SLC 500 (1746) |
| Distributed I/O | 1734-AENTR, 1734-IB8, 1734-IE2C, 1734-IB8S safety, 1794-AENTR, 5094-AENTR, 5069-IF8 |
| Operator terminals | PanelView Plus 7 10-inch, PanelView Plus 7 15-inch, PanelView 800, PanelView 5310 |
| Drives, motor control and networking | PowerFlex 525, PowerFlex 755, PowerFlex 4, 150-A180NBD SMC, Stratix 2000, 1783-NATR |
Ordering Allen-Bradley products: what we need
Send the full catalogue number and the series letter from the label (for example 1756-EN2T Series D), because firmware and compatibility can change between series. For drives, add the motor power, voltage and filter option. For a discontinued SLC 500 or MicroLogix part, tell us whether you need the exact spare or a migration proposal.
Facts checked against Rockwell Automation's published company history, October 2026.
Browse Allen-Bradley products by category: PLC & I/O Cards, AC Drives.
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Frequently Asked Questions
What makes the 1756-IB16D different from the IB16?
It has diagnostic inputs in groups of four and uses the 1756-TBCH terminal block.
What voltage range does it accept?
10 to 30 V DC, nominal 24 V DC.
How many points are in each group?
Four points per group.
What is the backplane draw?
150 mA at 5.1 V DC and 3 mA at 24 V DC.
Is the terminal block included?
No, order the 1756-TBCH separately.
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