Allen‑Bradley 1797‑OB4D FLEX Ex 24V DC Source Digital Output Module

Products Description

Allen Bradley 1797-OB4D FLEX Ex Source Digital 24V DC Output Module

Packing&Delivery

In order to save the freight and reduce your budget, we choose the packaging for environment-friendly. We use foam board with 3 cm thick to fill in all around the box inside to protect parts, then use carton to pack the parts, but if they are too heavy, we will customized the wooden box for them.Shipping term DHL Fedex TNT EMS UPS.

Key Features

• 4 Non-Isolated Sourcing Outputs – Positive-switching (PNP) outputs for 24V DC field devices 

• Intrinsic Safety – Eliminates the need for external safety barriers in hazardous locations 

• Wide Load Range – 30–5000 ohms supports diverse intrinsically safe solenoids and actuators 

• Electronic Protection – Lead break, overload, and short-circuit protection per channel 

• Comprehensive Diagnostics – Fault and overload alarm reporting to the controller via module data bits 

• Hot Swap Capability – Removal and insertion under power (RIUP) supported 

• Yellow Status LEDs – Individual channel output status indication; red flashing for fault detection 

• Visual Diagnostics – 4 yellow status LEDs, 1 green power LED, fault indication via flashing red LEDs 

Technical Specifications

Hazardous Location Certifications

The 1797‑OB4D is certified for installation in the following hazardous locations :

• Class I, Zones 0, 1, & 2 – Groups IIC, IIB, IIA

• Class I, Division 1 & 2 – Groups A, B, C, D

• Class II, Division 1 & 2 – Groups E, F, G

• Class III, Division 1 & 2 – Groups A‑G

Intrinsic Safety Entity Parameters

Each output channel can be connected to intrinsically safe devices with the following entity parameters :

Allowed External Capacitance and Inductance :

Terminal Base Entity Parameters (Male Bus Connector) 

System Integration Notes

Compatible Terminal Bases

The 1797‑OB4D must be used with an intrinsically safe terminal base unit :

• 1797‑TB3 – screw termination

• 1797‑TB3S – spring‑clamp termination

Important: The keyswitch on the terminal base must be rotated clockwise to position 7 for this module type . Do not change the position of the keyswitch after wiring the terminal base unit.

Wiring Requirements

• Terminals 2, 3, 6, 7, 10, 11, 14, 15, 17–32, 36–39, and 46–49 shall not be connected 

• Connect +V DC power to terminal 34 (and terminal 50) on the 34‑51 row 

• Connect -V DC power to terminal 35 (and terminal 51) 

• Wiring methods must be in accordance with the National Electric Code, ANSI/NFPA 70, Article 504 and 505, or the Canadian Electric Code CSA C22.1, Part 1, Appendix F 

• All I/O wiring must be suitable for intrinsically safe circuits; use blue‑jacketed cable where required by local standards 

Output Wiring Reference

+24V: C‑34 and C‑50 | Common: C‑35 and C‑51 

Diagnostics & Fault Detection

Status Indicators 

Module-Defined Data Types

The 1797‑OB4D provides the following diagnostic members accessible via RSLogix / Studio 5000 :

Note: To enable FaultAlarm and OverloadAlarm diagnostics, the DetectAlarms member must be set to 1 via programming .

Applications

The 1797‑OB4D is ideal for discrete output control in hazardous area automation :

• Oil & Gas – Control of pneumatic valve actuators, emergency shutdown solenoids, and warning beacons on wellhead equipment and offshore platforms

• Chemical Processing – Operation of reactor agitator motors, material transfer pumps, and ventilation damper actuators in Zone 2 areas

• Pharmaceutical Production – Activation of clean room air lock solenoids, sterile transfer valves, and environmental monitoring alarm lights

• Mining – Control of conveyor belt start/stop, dust suppression spray systems, and underground ventilation fan controls

• Food & Beverage – Management of CIP valve sequencing, ingredient dosing pumps, and packaging line diverter gates

Frequently Asked Questions (FAQ)

Q1: How many output channels does the 1797‑OB4D provide?

The module provides 4 non-isolated sourcing output channels .

Q2: What is the output type?

The 1797‑OB4D features current sourcing (PNP / high-side) outputs for 24V DC field devices. The module supplies positive voltage to the load, and the load connects between the output terminal and ground .

Q3: What is the load range for each output?

Each channel supports a load range of 30–5000 ohms, accommodating a wide variety of intrinsically safe solenoids, actuators, and indicators .

Q4: What terminal base does this module require?

The module must be installed on a 1797‑TB3 (screw) or 1797‑TB3S (spring‑clamp) intrinsically safe terminal base unit . The keyswitch must be set to position 7 .

Q5: Can I use this module with standard 1794 FLEX I/O terminal bases?

No. The 1797‑OB4D requires a 1797‑series terminal base. The FLEX Ex system uses a specialized intrinsically safe backplane architecture, making it incompatible with standard 1794 hardware .

Q6: What protection features are built into the module?

The module features lead break, overload, and short-circuit protection per channel . Faults are reported to the controller via diagnostic data bits .

Q7: What diagnostics are available on this module?

Each channel provides fault alarm and overload alarm reporting via module-defined data types. Individual channel LEDs indicate output state (yellow) and fault conditions (flashing red) .

Q8: What is the maximum operating temperature?

The module operates in ambient temperatures from -20°C to +70°C (-4 to +158°F) .

Q9: Can I replace this module while the system is powered?

Yes, the module supports Removal and Insertion Under Power (RIUP), allowing replacement without system shutdown .

Q10: Is this module intrinsically safe for hazardous areas?

Yes. The 1797‑OB4D is designed for intrinsically safe installation in Class I, Zones 0, 1, & 2 and Class I, II, III, Division 1 & 2 hazardous locations . It limits the energy discharged to the field to prevent ignition of flammable atmospheres.