Allen-Bradley 1756-OB16IS ControlLogix Output Module

1756-OB16IS 16-Channel Scheduled Isolated DC Output Module by Rockwell Automation

Product Introduction

The 1756‑OB16IS from Allen‑Bradley represents a high‑performance digital output solution for the ControlLogix system. Specifically, it provides 16 individually isolated output channels, and notably, 8 of these channels support scheduled outputs for time‑synchronized control. Furthermore, this module operates with a nominal 24 VDC, while also accommodating a wide 10–30 VDC range. Meanwhile, it supports both sink and source wiring configurations, offering excellent flexibility for various load types. Therefore, the scheduled output feature, enabled by CIP Sync™ architecture, makes the 1756‑OB16IS particularly suitable for motion control, printing, packaging, and other applications that demand precise output timing relative to a coordinated system time (CST).

Key Technical Specifications

The 1756‑OB16IS offers a unique combination of isolation and scheduling capability. For instance, each output is rated for 2A at 30 °C and 1A at 60 °C, while the total module current reaches 8A at 30 °C and 4A at 60 °C. Additionally, the module supports a surge current of 4A for 10 ms, which is repeatable every 2 seconds.

• Number of Outputs: 16 individually isolated (8 scheduled)

• Output Voltage Range: 10–30 VDC (nominal 24 VDC)

• Wiring Mode: Sink or source (user‑selectable per channel)

• Continuous Current per Point: 2 A @ 30 °C; 1 A @ 60 °C

• Continuous Current per Module: 8 A @ 30 °C; 4 A @ 60 °C

• Surge Current: 4 A for 10 ms, repeatable every 2 s at 60 °C

• Minimum Load Current: 1 mA per point

• Off‑State Leakage Current: 0.5 mA max per point

• On‑State Voltage Drop: 1.2 VDC max at 2 A

• Signal Delay (OFF to ON): 1 ms max

• Signal Delay (ON to OFF): 2 ms max

Regarding power consumption, the 1756‑OB16IS draws 350 mA at 5.1 VDC and 2.5 mA at 24 VDC from the backplane. Consequently, its total backplane power is a modest 1.8 W, with a maximum power dissipation of 3.6 W at 60 °C and thermal dissipation of 12.28 BTU/hr.

Scheduled Outputs and CIP Sync™ Integration

A standout feature of the 1756‑OB16IS is its 8 scheduled outputs. Specifically, these outputs synchronize within the Coordinated System Time (CST) of the CIP Sync™ network, thereby enabling precise timing for coordinated motion and process sequences. Moreover, the scheduled output update occurs within a 16.7 µs window, ensuring deterministic performance. As a result, this module is a critical component in applications requiring high‑speed, tightly synchronized I/O events, such as cam‑controlled motion or high‑speed packaging lines.

Isolation and Protection Features

The 1756‑OB16IS provides 250V continuous isolation (basic insulation) between output channels and the backplane, as well as between individual channels. For instance, this isolation is tested at 1350V AC for 2 seconds, ensuring robust protection against electrical noise and ground loops. Furthermore, each output is current‑limited and includes electronic short‑circuit protection. However, it is important to note that the module does not have internal fusing; therefore, external fuses are recommended for each output circuit to ensure complete protection.

Configuration and Fault Management

The 1756‑OB16IS supports flexible configuration through the Logix programming environment. For example, you can set fault‑mode and program‑mode states per point, with options of Hold Last State, On, or Off. Notably, the default is Off, which enhances safety during controller faults. In addition, the module supports rack‑optimized and scheduled communication formats, making it compatible with both standard and time‑critical control architectures.

Installation and Mounting Guidelines

Installing the 1756‑OB16IS follows standard ControlLogix practices. First, it occupies one slot and fits into any available position in a ControlLogix chassis, except the leftmost slot reserved for the processor or communication adapter. Next, follow these simple steps:

• Step 1: Power down the chassis before installation.

• Step 2: Align the 1756‑OB16IS with the card guides in your chosen slot.

• Step 3: Slide the module firmly into the backplane until it locks.

• Step 4: Attach a compatible removable terminal block (RTB). For this purpose, the module uses a 36‑pin RTB; compatible models include 1756‑TBCH (screw) and 1756‑TBS6H (spring).

• Step 5: Wire your DC loads to the RTB terminals. Meanwhile, remember that each output can be wired as sink or source.

• Step 6: Power on the chassis and configure the module via your Logix software. Finally, set the RPI, scheduled output timing, and fault states as required for your application.

Additionally, the module supports hot‑swapping (insertion under power) when the system allows, thereby minimizing downtime during maintenance.

Packaging List

Your shipment of the 1756‑OB16IS includes the following:

• One (1) Allen‑Bradley 1756‑OB16IS ControlLogix scheduled isolated output module

• Removable terminal block (RTB) – choose 1756‑TBCH or 1756‑TBS6H at order

• Installation instructions leaflet

• Anti‑static protective packaging

Note: This package does not include calibration certificates, warranty documents, fuses, or software media.

Shipping and Delivery

We ship the 1756‑OB16IS worldwide using trusted express carriers: FedEx, UPS, and DHL. Specifically, orders are processed within 24 business hours, and tracking information is provided promptly upon dispatch.

Frequently Asked Questions (FAQ)

1. What does "scheduled output" mean on the 1756‑OB16IS?
The 1756‑OB16IS has 8 outputs that can be precisely timed using the Coordinated System Time (CST) from CIP Sync™. Consequently, this allows output changes to occur at a specific system time, which is essential for synchronized motion and high‑speed applications.

2. Can the 1756‑OB16IS be used as both sink and source?
Yes. Specifically, each output on the 1756‑OB16IS can be configured individually as sink or source, thereby offering flexibility for different load wiring requirements.

3. Which removable terminal blocks work with the 1756‑OB16IS?
The 1756‑OB16IS uses 36‑pin RTBs. Therefore, compatible models are 1756‑TBCH (screw‑type) and 1756‑TBS6H (spring‑clamp).

4. Is the 1756‑OB16IS compatible with standard ControlLogix chassis?
Yes. Specifically, the 1756‑OB16IS fits into any standard ControlLogix chassis, including 1756‑A4, 1756‑A7, 1756‑A10, 1756‑A13, and 1756‑A17.

5. Does the 1756‑OB16IS require a special firmware version?
The 1756‑OB16IS requires a ControlLogix controller and firmware that support CIP Sync™ and scheduled outputs. Therefore, please verify your system compatibility before installation.