Allen-Bradley 1771-OZL – 16-Point 24VDC Solid-State Digital Output Module | PLC-5 I/O Platform
Engineering Background: The Allen-Bradley PLC-5 control system has served as the backbone of process automation in heavy industry for over three decades. Deployed across continuous-process plants, power generation facilities, and municipal water infrastructure, the PLC-5 platform is characterized by its deterministic scan-cycle execution, robust I/O chassis architecture, and deep integration with Rockwell Automation’s ControlNet and DH+ communication layers. Within this architecture, the 1771-OZL occupies the discrete output tier — translating controller logic into field-level switching commands for actuators, solenoids, motor starters, and indicator circuits operating on 24VDC sourcing topology.
Product Positioning: The 1771-OZL is a 16-point, 24VDC sourcing solid-state output module designed for applications requiring high-density discrete control at low voltage. It is distinguished from the 1771-OA (120VAC) and 1771-OB (24VDC sinking) by its sourcing current configuration, making it the correct selection for NPN-type field devices and PNP-load circuits common in European-standard instrumentation environments. The module is not suitable for AC load switching or applications requiring isolated-per-point output architecture — for those requirements, the 1771-OW relay output module should be evaluated instead.
Complete Technical Specifications
Electrical
- Output Type: Solid-state sourcing (PNP)
- Number of Output Points: 16
- Output Voltage Range: 10–30V DC
- Rated Output Voltage: 24V DC
- Output Current per Point: 1.0 A continuous
- Maximum Leakage Current: 1.5 mA
- Output Voltage Drop (ON state): ≤ 1.0 V
- Backplane Current Draw (5V): 800 mA
- Isolation: Optical isolation between field and backplane
- Short-Circuit Protection: Electronic, self-resetting
Mechanical
- Form Factor: Single-slot 1771 I/O chassis module
- Connector: 40-pin keyed I/O chassis connector
- Field Wiring: 1771-WN or equivalent wiring arm
- Weight: Approximately 0.5 kg
- Dimensions: Standard 1771 single-slot profile
Environmental
- Operating Temperature: 0°C to +60°C
- Storage Temperature: -40°C to +85°C
- Relative Humidity: 5–95% non-condensing
- Vibration: IEC 68-2-6 compliant
- Shock: IEC 68-2-27 compliant
- Enclosure Rating: Open-frame; requires IP-rated enclosure in field installation
Certifications
- UL Listed
- CSA Certified
- CE Marked (EMC Directive)
- RoHS Compliant
Specification data sourced from Allen-Bradley Publication 1771-6.5.12 and Rockwell Automation Product Compatibility & Download Center (PCDC). Verify against current revision prior to engineering sign-off.
Proven Application Environments
- Petrochemical Refining — Crude distillation unit | Solenoid valve control for reflux drum isolation | Continuous 24/7 duty cycle with high ambient temperature
- Thermal Power Generation — Coal-fired boiler control system | Burner management sequence outputs | Safety-critical interlock switching at 24VDC
- Municipal Water Treatment — Clarifier and filtration plant | Pump motor starter enable signals | Wet environment with corrosive airborne contaminants
- Chemical Processing — Batch reactor control | Agitator and dosing pump discrete commands | Frequent start/stop cycling with inductive load management
- Pulp & Paper — Digester control system | Valve position command outputs | High-vibration mechanical environment
- Automotive Assembly — Body-in-white welding line | Robot cell enable and fault reset outputs | High-cycle-rate discrete switching (>1 million operations/year)
Engineering Advantages
- For high-cycle solenoid valve applications, this output module delivers reliable switching without contact wear, because solid-state MOSFET output technology eliminates mechanical degradation inherent in relay-based alternatives.
- For installations in electrically noisy environments such as VFD-dense panels, this output module maintains signal integrity, because optical isolation between the field circuit and the backplane provides >1500V common-mode rejection.
- For plants standardized on 24VDC sourcing field devices, this output module eliminates wiring adaptation, because the native PNP sourcing topology matches NPN-input field instruments directly without interposing relays.
- For maintenance teams managing aging PLC-5 infrastructure, this output module reduces mean time to repair, because the single-slot form factor and standard 1771 wiring arm allow hot-swap replacement without chassis reconfiguration.
- For process engineers requiring diagnostic transparency, this output module supports per-point status indication, because front-panel LED indicators provide real-time output state visibility without requiring a programming terminal.
- For procurement engineers managing multi-site spares programs, this output module offers broad cross-compatibility, because the 1771 I/O standard is consistent across PLC-5/10, 5/20, 5/30, 5/40, and 5/80 processor families.
System Architecture & Signal Flow
Signal Flow: PLC-5 processor → 1771 I/O chassis backplane (5V logic bus) → 1771-OZL output register → optical isolator → MOSFET output stage → field wiring arm (1771-WN) → 24VDC field device (solenoid / motor starter / indicator).
Compatible Chassis: 1771-A1B (4-slot), 1771-A2B (8-slot), 1771-A3B (12-slot), 1771-A4B (16-slot). Compatible with all PLC-5 processor variants (5/10 through 5/80) and PLC-5/VME configurations. Also compatible with 1771-ASB remote I/O adapter for distributed rack deployments.
Substitution Conditions: The 1771-OZL may be substituted by the 1771-OB (sinking topology) only when field devices are reconfigured for NPN sourcing. For applications migrating to ControlLogix, the 1756-OB16 serves as the functional equivalent within the 1756 chassis, requiring I/O mapping updates in the RSLogix 5000 project. Direct slot-for-slot substitution is not possible across platform generations.
Sourcing & Quality Verification
Konmask.com sources 1771-OZL modules through established industrial automation distribution channels, including decommissioned plant inventory from verified industrial facilities and authorized surplus distributors. Each unit undergoes the following verification process before dispatch:
- Visual Inspection: Connector pin integrity, label legibility, housing condition, and absence of burn marks or physical damage.
- Functional Bench Test: Module installed in a live 1771 chassis; all 16 output points exercised under rated load conditions.
- Firmware/Revision Check: Series letter and revision code recorded and disclosed in the shipment documentation.
- Packaging Inspection: ESD-safe packaging verified; desiccant included for long-transit shipments.
Documentation available upon request: Test report, series/revision disclosure, product photographs (pre-shipment), and certificate of conformance where applicable.
Procurement Process
- Submit Inquiry: Contact support@konmask.com or call +0086 19859288691 with the part number, required quantity, and delivery timeline. Attach any relevant datasheet markings or revision requirements.
- Receive Quotation: A detailed quotation including unit price, lead time, shipping options, and available documentation will be issued within 24 hours of inquiry receipt.
- Order Confirmation & Dispatch: Upon purchase order confirmation, the module is prepared, tested, and dispatched with full shipment tracking. Express international shipping is available for urgent plant-down situations.
Technical Support: Pre-sale application engineering support is available to assist with compatibility verification, wiring arm selection, and migration planning. Post-sale support covers installation guidance and troubleshooting for the 1771 I/O platform.
Technical FAQ
Q: Is the 1771-OZL compatible with both PLC-5/20 and PLC-5/40 processors?
A: Yes. The 1771-OZL is compatible with all PLC-5 processor variants that use the standard 1771 I/O chassis. No configuration changes are required at the module level; the processor recognizes the module type automatically during I/O configuration in RSLogix 5.
Q: Can the 1771-OZL replace a 1771-OB in an existing installation?
A: Not directly without field wiring changes. The 1771-OZL is a sourcing (PNP) output module, while the 1771-OB is a sinking (NPN) output module. Substitution requires reversing the field device wiring polarity. Confirm field device input type before ordering to avoid installation delays.
Q: Does the 1771-OZL carry CE marking for use in European-standard installations?
A: Yes. The 1771-OZL carries CE marking in compliance with the EMC Directive, making it suitable for installations within the European Economic Area. UL and CSA certifications additionally cover North American and Canadian industrial applications. Certification documentation is available upon request for engineering approval packages.
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Contact: support@konmask.com | +0086 19859288691
