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Description
Technical Specifications
| Product Model | 1734-OB8S |
|---|---|
| Manufacturer | Rockwell Automation / Allen-Bradley |
| Product Type | POINT Guard I/O 8-Channel Safety Sourcing Digital Output Module |
| Number of Outputs | 8 (Sourcing / PNP, Solid-State MOSFET) |
| Nominal Output Voltage | 24 V DC (Operating Range 19.2–28.8 V DC) |
| Max Output Current per Point | 1.0 A continuous @ 60 °C (0.5 A @ 30 °C per some catalog limits) |
| Max Total Module Output Current | 8.0 A (all channels combined) |
| On-State Voltage Drop | ≤ 0.5 V DC typical @ rated current |
| Off-State Leakage Current | ≤ 0.1 mA |
| Field Supply Requirement | External 24 V DC (separate from I/O bus power) |
| Backplane Bus Current Draw | 190 mA max @ 5 V DC; 5 mA @ 24 V DC (module power) |
| Safety Certification | IEC 61508 SIL 2 (single-ch), SIL 3 / EN ISO 13849-1 Cat. 4 PLe (dual-ch w/ safety PLC); TÜV certified |
| Response / Update Time | ≤ 6.2 ms (typical safety output response) |
| Isolation | Basic insulation 50 V DC continuous between field side and system side; no isolation between channels |
| Pulse Test Feature | Yes — safety pulse test per channel (475 µs pulse width, 575 ms period) for cross-short / wire-break detection |
| Indicators | 1 Green/Yellow Module Status (MS), 1 Yellow Network Status (NS), 8 Green Point Status LEDs |
| Mounting | 35 mm DIN Rail via 1734-TB / 1734-TBS terminal base (Requires POINT I/O Adapter e.g. 1734-AENT) |
| Dimensions (H×W×D) | 77 × 12.5 × 55 mm (3.03 × 0.49 × 2.17 in) excluding terminal base |
| Operating Temp. | -20 °C to +55 °C (-4 °F to +131 °F) |
| Weight | Approx. 62 g (0.14 lb) excluding terminal base |
| Approvals | cULus Listed, CE, C-Tick, TÜV, ATEX / IECEx Class I Zone 2 / Class II Zone 22 |
Main Features and Advantages
Certified functional safety integration: The Allen-Bradley 1734-OB8S is TÜV-certified for use in safety instrumented functions up to SIL 2 in single-channel mode and SIL 3 / Performance Level e (Cat. 4) when operated in dual-channel redundant mode under a GuardLogix or SmartGuard safety controller. This makes it suitable for controlling safety-rated contactors, enabling servo power, or activating safety interlock releases in compliance with machinery directive requirements.Integrated output pulse-test diagnostics: Each output channel on the Allen-Bradley 1734-OB8S can perform an automatic safety pulse test that momentarily pulses the output OFF to verify the absence of a short-to-ground or cross-wiring fault. This diagnostic runs transparently in the background without affecting normal machine operation, allowing early detection of wiring degradation while avoiding unnecessary process interruptions—a key advantage over standard non-safety digital output modules.Flexible single/dual-channel operation: The Allen-Bradley 1734-OB8S can be configured in software for single-channel safety output (simpler applications, SIL 2 / PL d) or paired with another output in dual-channel mode for redundant verification (SIL 3 / PLe). This flexibility lets the same hardware serve both moderate-risk and high-integrity safety applications, reducing spare parts inventory for machine builders.Electronic short-circuit and overload protection: All eight sourcing outputs on the Allen-Bradley 1734-OB8S are individually protected against short circuits and overcurrent conditions. Upon detecting a fault, the affected channel shuts down and reports the diagnostic to the controller via the I/O adapter; healthy channels continue to operate normally, localizing faults and simplifying troubleshooting.Compact footprint with hot-swap support: At only 12.5 mm wide, the Allen-Bradley 1734-OB8S conserves valuable DIN-rail space in crowded enclosures. The module supports Remove and Insert Under Power (RIUP), meaning it can be replaced without powering down the entire I/O rack—critical for minimizing downtime during maintenance on running production lines. Per-point LEDs give immediate visual confirmation of output state and assist field technicians during commissioning and fault-finding.
Application Field
The Allen-Bradley 1734-OB8S is deployed wherever safety-rated discrete actuation is required in a distributed I/O topology. In automotive assembly and body-shop lines, the Allen-Bradley 1734-OB8S controls safety-rated contactors that enable 24 V DC power to robot grippers, light curtains’ reset circuits, or perimeter gate unlock solenoids—always under the supervision of a GuardLogix safety PLC that monitors the module’s dual-channel feedback and pulse-test results. Packaging and converting machines use the Allen-Bradley 1734-OB8S to safely energize pneumatic valve banks for guard-door interlocks or to command external safety relay modules that cut main drive power when an E-Stop is triggered.In process skids and hybrid batch systems, the Allen-Bradley 1734-OB8S drives safety-rated beacons, audible alarms, and permissive signals to local motor starters, ensuring that hazardous energy can only be applied when all preconditions (guard closed, light curtain clear, reset pressed) are satisfied and continuously verified by the safety controller. Because the module communicates over CIP Safety via EtherNet/IP (with a 1734-AENTR or 1734-AENT adapter) or DeviceNet (with 1734-ADN), it is equally at home in greenfield installations and retrofits where running dedicated safety wiring back to a central cabinet would be impractical or cost-prohibitive.Machine builders exporting globally benefit from the Allen-Bradley 1734-OB8S carrying CE, cULus, and TÜV functional safety marks, as well as ATEX / IECEx Zone 2/22 approvals for installation in potentially explosive atmospheres when mounted in a suitably certified enclosure. The combination of certified safety outputs, compact form factor, and seamless integration with Rockwell Automation safety controllers makes the Allen-Bradley 1734-OB8S a preferred choice for functional safety implementations in discrete manufacturing, material handling, pharmaceutical processing, and food & beverage packaging applications.
Related Products
1734-IB8S — POINT Guard I/O 8-channel Safety Sinking Digital Input Module; complements the 1734-OB8S by providing certified safety input monitoring (E-Stops, guard switches, light curtains).1734-OB8 — Standard (non-safety) 8-channel 24 V DC sourcing digital output module; use when safety certification is not required for the same I/O rack.1734-OBV2S — POINT Guard I/O 2-channel high-current safety sourcing output module (typically for direct control of larger safety contactors); alternative when fewer but higher-spec safety outputs are needed.1734-AENT / 1734-AENTR — EtherNet/IP POINT I/O Adapter (standard / safety-rated with CIP Safety); required to connect the 1734-OB8S to a ControlLogix/CompactLogix/GuardLogix Ethernet network.1734-TB / 1734-TBS — 8-point removable screw terminal base (standard / spring clamp); the 1734-OB8S must be mounted on one of these terminal bases for field wiring.1734-ADN — DeviceNet POINT I/O Adapter; alternative adapter for integrating the 1734-OB8S into legacy DeviceNet safety networks with a SmartGuard 600 controller.
Installation and Maintenance
Pre-installation preparation: Before installing the Allen-Bradley 1734-OB8S, ensure you have selected a compatible POINT I/O adapter (1734-AENTR for CIP Safety over EtherNet/IP is recommended) and a suitable terminal base such as the 1734-TB (screw) or 1734-TBS (spring clamp). Verify that the external 24 V DC field supply (19.2–28.8 V) is isolated and properly fused, and that the I/O rack has an adequate 5 V DC backplane power budget (the Allen-Bradley 1734-OB8S draws up to 190 mA from the 5 V bus). Snap the terminal base onto a clean 35 mm DIN rail, then align the Allen-Bradley 1734-OB8S module with the base keying and press firmly until it seats with an audible click. Wire the field supply to the terminal base’s V+/V− terminals and connect load commons appropriately for sourcing (PNP) outputs. Use Studio 5000 Logix Designer to add the module to the I/O configuration tree and assign safety tag names; the safety signature must be accepted before the module goes online.Maintenance recommendations: The Allen-Bradley 1734-OB8S is a solid-state device with no user-serviceable components. Routine checks should include verifying that the Module Status (MS) LED is solid green (indicating a valid connection to the safety controller and passed self-test) and that individual point LEDs reflect expected output states. If MS flashes red or the Network Status (NS) LED indicates a fault, consult the controller’s I/O fault list for diagnostic codes—common causes include loss of safety signature, field supply undervoltage, or detected cross-circuit fault on an output. The module supports RIUP, so a faulty Allen-Bradley 1734-OB8S can be removed and replaced live; upon reinsertion, the safety controller will prompt for re-acceptance of the safety signature before returning the outputs to service. Periodically inspect terminal screw torque (recommended 0.5–0.6 N·m / 4.4–5.3 lb·in) and clean dust from the enclosure to prevent overheating. Never open the module housing.
