Allen-Bradley 1756-OF6VI ControlLogix Analog Output Module

1756-OF6VI Isolated Voltage Module 6-Point by Rockwell

Product Introduction

The 1756‑OF6VI from Allen‑Bradley is a high‑performance analog output module designed for the Rockwell Automation ControlLogix system. It provides six individually isolated voltage output channels, making it an ideal choice for applications that demand signal integrity and noise immunity. Each channel supports a ±10 VDC output range and delivers a fine resolution of 14 bits across 21V (1.3 mV per bit). This module fits into a single chassis slot and works seamlessly with Logix controllers for local or distributed I/O architectures.

Key Technical Specifications

The 1756‑OF6VI offers robust analog output capabilities. It features six isolated channels, meaning each output is electrically separated from the others and from the backplane. This design significantly reduces ground loops and interference. The output resolution reaches 14 bits over 21V, with 13 bits plus a sign bit over 10.5V. The module uses an R‑Ladder DAC conversion method, ensuring monotonicity with no missing codes.

• Output Channels: 6 individually isolated, voltage

• Output Signal Range: ±10 VDC (selectable)

• Resolution: 14 bits across 21V (1.3 mV); 13 bits across 10.5V + sign bit

• Data Formats: Integer mode (left‑justified, 2’s complement) and IEEE 32‑bit floating‑point

• Calibrated Accuracy: Better than 0.1% of range

• Module Error: 0.5% of range

• Settling Time: < 2 ms to 95% of final value (resistive load)

• Output Drive Capability: > 1000 Ω loads, 10 mA maximum

• Output Impedance: 1 Ω

For power consumption, the 1756‑OF6VI draws 250 mA at 5.1V DC and 175 mA at 24V DC from the backplane. Its total backplane power dissipation is 5.5W, with a thermal dissipation of 16.54 BTU/hr. The module also includes comprehensive protection features. It offers overvoltage protection up to ±24 VDC and electronic current‑limited short‑circuit protection on each output.

Isolation and Environmental Ratings

Isolation is a standout feature of the 1756‑OF6VI. It provides 250V continuous isolation (basic insulation) between output channels and the backplane, as well as between channels. This isolation is tested at 1350V AC for 2 seconds, ensuring reliable operation in noisy industrial environments. The module carries a T4A temperature code (North America) and IEC T4 rating.

For environmental resilience, the 1756‑OF6VI operates within a temperature range of 0 to 60 °C and functions in 5–95% non‑condensing humidity. It can withstand operational shocks of 30G and vibrations of 2G at 10–500 Hz. Its open‑style enclosure is suitable for panel mounting inside a protected control cabinet.

Performance and Calibration

The 1756‑OF6VI supports onboard data alarming, real‑time channel sampling, and scaling to engineering units. Its maximum module scan time is 25 ms for floating‑point data and 10 ms for integer data. To maintain accuracy, Allen‑Bradley recommends recalibration every six months. The module exhibits a typical offset drift of 60 µV/°C and a gain drift of 80 ppm/°C.

Additionally, the 1756‑OF6VI does not include open‑circuit detection, but its overvoltage and short‑circuit protections are more than adequate for most industrial applications.

Installation and Mounting Guidelines

Installing the 1756‑OF6VI is straightforward. It occupies one slot in a ControlLogix chassis and can be placed in any available slot on the backplane.

• Step 1: Ensure the chassis is powered off before installation.

• Step 2: Align the module with the card guides in the chosen slot.

• Step 3: Slide the 1756‑OF6VI firmly into the backplane connector until the locking mechanism clicks.

• Step 4: Attach the removable terminal block (RTB). This module is compatible with 1756‑TBNH, 1756‑TBSH, and 1756‑TBCH RTBs.

• Step 5: Wire your voltage output signals according to the terminal block labeling.

• Step 6: Power on the chassis and configure the module via your Logix programming software.

The module’s design also supports hot‑swapping (insertion under power) when the system allows, minimizing downtime during maintenance.

Packaging List

When you order the 1756‑OF6VI, your shipment includes the following items:

• One (1) Allen‑Bradley 1756‑OF6VI ControlLogix analog output module

• Removable terminal block (RTB) – please specify preference for 1756‑TBNH (screw) or 1756‑TBSH (spring)

• Installation instructions leaflet

• Anti‑static packaging for safe transport

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

Shipping and Delivery

We ship the 1756‑OF6VI via global express carriers, including FedEx, UPS, and DHL. All orders are processed within 24 hours on business days. Tracking information is provided as soon as the package leaves our warehouse.

Frequently Asked Questions (FAQ)

1. What type of removable terminal block is compatible with the 1756‑OF6VI?
The 1756‑OF6VI works with 1756‑TBNH (screw‑type) and 1756‑TBSH (spring‑clamp) terminal blocks. It also accepts 1756‑TBCH for standard connections.

2. Can the 1756‑OF6VI be used in a distributed I/O architecture?
Yes. The 1756‑OF6VI functions not only as a local I/O module but also as a component in a distributed ControlLogix I/O network via the backplane.

3. What is the difference between the 1756‑OF6VI and 1756‑OF6CI?
The 1756‑OF6VI provides voltage outputs (±10 VDC), while the 1756‑OF6CI is a current output module (0‑20 mA or 4‑20 mA). Both offer six isolated channels but serve different signal types.

4. How often should I calibrate the 1756‑OF6VI?
Allen‑Bradley recommends recalibrating the 1756‑OF6VI every six months to maintain its specified accuracy and drift performance.

5. Does the module support real‑time sampling?
Absolutely. The 1756‑OF6VI supports real‑time channel sampling, onboard alarming, and scaling to engineering units, making it suitable for demanding process control loops.