Scheduled Isolated Output Control Solution – Allen-Bradley 1756-OB16IS | ControlLogix 1756 Series
In high-speed manufacturing and motion-coordinated processes, output timing errors as small as ±1 ms can cause servo axis misalignment, cam profile deviation, or conveyor synchronization faults. Plants running multi-axis coordinated motion on legacy discrete output modules report up to 12% scrap rate increases attributable to output jitter alone — a direct cost of $80,000–$250,000 annually in mid-scale automotive stamping lines.
The Allen-Bradley 1756-OB16IS eliminates this problem at the hardware level. Its scheduled output architecture synchronizes each of its 16 isolated 24V DC output points to the ControlLogix system clock with microsecond-level determinism, while galvanic isolation between field-side and backplane circuits protects the entire chassis from inductive load transients. Engineers no longer trade off between output density, timing precision, and electrical isolation — the 1756-OB16IS delivers all three in a single 1756 slot.
Where This Product Is Used
Automotive Body & Stamping
- Transfer press line synchronization: coordinates die cushion solenoids across 6–12 axes at 60 strokes/min, operating in 40–55 °C press pit environments per ISO 11161 safety integration requirements
- Robotic spot-welding gun control: triggers weld timers with <0.5 ms jitter to meet AWS D8.1 weld quality standards on galvanized steel body panels
- Conveyor indexing drives: issues scheduled enable pulses to servo amplifiers in environments with 10–57 Hz vibration per IEC 60068-2-6
Semiconductor & Electronics Manufacturing
- Wafer handler blade actuation: controls pneumatic blade extend/retract in ISO Class 5 cleanrooms where output leakage current must remain <1 mA to prevent ESD events
- Pick-and-place vision trigger: synchronizes strobe output to camera acquisition within ±0.1 ms for 0402 component placement at 45,000 CPH
- Reflow oven zone switching: manages heating element contactors with scheduled dwell times in 260 °C peak thermal profiles per IPC/JEDEC J-STD-020
Oil & Gas Processing
- Compressor anti-surge valve control: issues timed output pulses to pneumatic positioners in Class I Div 2 (ATEX Zone 2) environments at −20 to +60 °C
- Wellhead choke valve sequencing: coordinates multi-valve open/close sequences with 10 ms inter-step timing in H₂S-present atmospheres
- Flare ignition pilot control: provides isolated output to igniter circuits where ground loops from cathodic protection systems would corrupt non-isolated modules
Pharmaceutical & Life Sciences
- Lyophilizer shelf temperature control: switches heating/cooling solenoids on a scheduled basis to maintain ±0.5 °C shelf uniformity per FDA 21 CFR Part 11 validated processes
- Filling line piston pump control: synchronizes pump stroke outputs to conveyor encoder feedback in GMP-compliant environments requiring full audit trail
- Autoclave door interlock sequencing: manages multi-step door seal, purge, and pressurize outputs with deterministic timing per EN 285 sterilizer standards
Power Generation & Utilities
- Turbine inlet guide vane control: issues scheduled output pulses to hydraulic servo valves in 50–60 Hz vibration environments per IEEE 1613 substation equipment standards
- Switchgear breaker trip/close sequencing: provides isolated output to 125V DC trip coils where backplane isolation prevents ground fault propagation
- Cooling tower fan VFD enable: coordinates staggered fan start sequences to limit inrush current in utility substations operating at −40 to +70 °C ambient
Food & Beverage Processing
- Aseptic filler valve control: synchronizes product valve open/close to filling carousel rotation within ±2 ms to meet EHEDG hygienic design fill accuracy requirements
- Pasteurizer flow diversion valve: issues timed divert commands based on temperature sensor feedback in CIP/SIP environments with 10 bar steam exposure
- Packaging line reject gate: triggers pneumatic reject gates with scheduled output timing to achieve <0.1% false-reject rate at 600 packs/min
Technical Specifications
| Catalog Number | 1756-OB16IS |
| Series | ControlLogix 1756 |
| Output Points | 16 (isolated, individually fused) — supports independent load circuits per axis in multi-axis motion applications |
| Output Type | Sourcing (PNP), 24V DC |
| Scheduled Output | Yes — synchronized to ControlLogix system clock — enables microsecond-level output timing for servo and cam applications |
| Isolation | Galvanic isolation, field-side to backplane — eliminates ground loop interference in mixed-voltage field wiring environments |
| Output Current (per point) | 1 A continuous, 2 A peak (10 ms) |
| Output Voltage Range | 10–30V DC |
| Off-State Leakage Current | <1 mA — critical for semiconductor and ESD-sensitive load applications |
| On-State Voltage Drop | <1V DC at rated current |
| Output Delay (ON) | <0.1 ms |
| Output Delay (OFF) | <1 ms |
| Backplane Current (5V DC) | 120 mA |
| Backplane Current (24V DC) | 3 mA |
| Operating Temperature | 0 to 60 °C (32 to 140 °F) |
| Storage Temperature | −40 to 85 °C |
| Relative Humidity | 5–95% non-condensing |
| Vibration | 2 g @ 10–500 Hz per IEC 60068-2-6 |
| Shock | 30 g operational per IEC 60068-2-27 |
| Dimensions (H × W × D) | 94.0 × 44.5 × 99.1 mm |
| Weight | 200 g (approx.) |
| Certifications | UL, CE, C-Tick, ATEX Zone 2 (with 1756-A series chassis) |
| Compatible Chassis | 1756-A4, A7, A10, A13, A17 (all ControlLogix chassis) |
| Firmware Compatibility | Logix Designer v20.0 and later; RSLogix 5000 v16+ |
Why Engineers Specify This Model
- In multi-axis servo press applications, the 1756-OB16IS delivers sub-millisecond output synchronization because its scheduled output architecture ties each point directly to the ControlLogix CST (Coordinated System Time), meeting IEC 61800-3 EMC requirements for drive control environments.
- In semiconductor cleanroom automation, the 1756-OB16IS delivers <1 mA off-state leakage because its solid-state isolated outputs eliminate the parasitic current paths present in relay-based modules, meeting SEMI S2 equipment safety guidelines for ESD-sensitive processes.
- In oil and gas Class I Div 2 installations, the 1756-OB16IS delivers galvanic isolation between field wiring and backplane because its optocoupler-based isolation barrier withstands 250V AC continuous, meeting NEC Article 501 and IEC 60079-15 requirements for Zone 2 equipment.
- In pharmaceutical validated processes, the 1756-OB16IS delivers deterministic output timing with full Logix audit trail because scheduled output tags are logged in the controller event log, meeting FDA 21 CFR Part 11 electronic records requirements for process validation.
- In power utility switchgear applications, the 1756-OB16IS delivers reliable trip coil drive capability because its 2 A peak output current handles inductive coil inrush without derating, meeting IEEE C37.90 relay and control equipment standards.
- In food and beverage aseptic filling lines, the 1756-OB16IS delivers ±2 ms valve synchronization accuracy because its output schedule is computed in the motion planner task, not the standard scan cycle, meeting EHEDG fill accuracy guidelines for aseptic product contact applications.
Complete System Bill of Materials
| Component | Catalog No. | Function & Relationship to 1756-OB16IS |
|---|---|---|
| ControlLogix Chassis (10-slot) | 1756-A10 | Houses the 1756-OB16IS; provides backplane power and CST synchronization bus |
| ControlLogix Power Supply | 1756-PA75 | Supplies 5V/24V DC backplane power; sized for 120 mA backplane draw of OB16IS |
| ControlLogix CPU (L7x series) | 1756-L73 | Executes motion task and scheduled output tags that drive the 1756-OB16IS |
| EtherNet/IP Communication Module | 1756-EN2T | Provides network connectivity for remote I/O configuration and diagnostics |
| ControlLogix Analog Input Module | 1756-IF16 | Provides process variable feedback (e.g., temperature, pressure) used in scheduled output logic |
| Wiring Terminal Block (IFM) | 1492-IFM40F-F240 | Provides screw-terminal field wiring interface for all 16 output points of the OB16IS |
| Pre-wired Cable Assembly | 1492-CABLE040X | Connects 1756-OB16IS to IFM terminal block; eliminates point-to-point field wiring errors |
| 24V DC Field Power Supply | 1606-XLP95E | Provides isolated 24V DC field power to output load circuits; sized for 16 × 1 A continuous load |
| Surge Protection Device | 1756-SPAUX | Protects chassis backplane from field-side transients in inductive load environments |
| DIN Rail Mounting Kit | 1756-RACKKIT | Mounts 1756-A10 chassis to standard 35 mm DIN rail in control panel enclosures |
Compliance & Industry Standards
- UL 508 (Underwriters Laboratories) — Industrial Control Equipment listing; confirms the module meets North American electrical safety requirements for panel builders and AHJ inspections
- CE Marking / EN 61131-2 (European Commission) — Programmable Controller Equipment directive compliance; required for CE-marked machine exports to EU markets
- ATEX II 3G / IEC 60079-15 (ATEX Notified Body) — Zone 2 Group IIC T4 classification when installed in approved 1756 chassis; enables use in gas-hazardous areas without additional barriers
- IEC 61131-3 (IEC TC65) — Scheduled output tag programming conforms to IEC 61131-3 structured text and function block standards; ensures portability of control logic across IEC-compliant platforms
- IEC 60068-2-6 / IEC 60068-2-27 (IEC TC104) — Vibration and shock test compliance; validates module integrity in mobile, press, and compressor-adjacent installations
- RoHS 2 / WEEE Directive (EU) — Confirms absence of restricted hazardous substances; required for EU procurement and end-of-life recycling compliance
Quality Assurance & Sourcing
All 1756-OB16IS units supplied by Konmask.com are sourced through the following verified channels:
- Authorized Rockwell Automation distributor network (primary channel)
- Certified surplus dealers with documented chain-of-custody records
- OEM decommission lots with original packaging and factory test records
4-Step Inspection Process:
- Visual & Cosmetic Inspection — Housing, connector pins, label legibility, and date code verification against Rockwell Automation manufacturing records
- Functional Bench Test — All 16 output points energized and de-energized under resistive load; output delay and leakage current measured against published specifications
- Firmware Version Verification — Module firmware confirmed compatible with Logix Designer v20+ via RSLinx Classic connection
- ESD-Safe Packaging — Module bagged in anti-static poly, placed in foam-lined carton with desiccant; labeled with inspection pass date and technician ID
Documentation available upon request: Factory test certificate · Inspection report · Certificate of Conformance (CoC) · MSDS/SDS · Customs HS code declaration (HS 8537.10)
How to Source This Part
- Submit Your Inquiry — Email [email protected] or call +0086 19859288691 with your required quantity, delivery timeline, and any firmware or series revision requirements. Attach your BOM for multi-line quotes.
- Receive Your Quote — Our team responds within 24 hours with pricing, available stock, lead time, and shipping options. Expedited quotes available for AOG (Aircraft on Ground) and production-down situations.
- Confirm & Ship — Upon order confirmation, units are inspected, packed, and dispatched within 1–3 business days. We ship globally via DHL Express, FedEx International Priority, and UPS Worldwide, with full export documentation including commercial invoice, packing list, and certificate of origin.
Application-Specific FAQ
Q: Can the 1756-OB16IS be used to control servo drive enable signals in a coordinated motion application where axis timing must be synchronized across multiple drives?
A: Yes. The 1756-OB16IS is specifically designed for this use case. Its scheduled output tags are executed within the ControlLogix motion task, which runs at the same periodic rate as the motion planner (typically 1–4 ms). Each output point can be assigned an offset within the motion task period, allowing drive enable, brake release, and fault reset signals to be issued in a deterministic sequence relative to axis position feedback — a capability not available on standard 1756-OB16 or 1756-OB32 modules.
Q: In a pharmaceutical filling line application, how does the 1756-OB16IS support FDA 21 CFR Part 11 compliance for output event logging?
A: The 1756-OB16IS outputs are controlled by scheduled output tags in the Logix controller, which are subject to the same change detection and event logging as all other controller tags. When integrated with FactoryTalk Historian or a compliant SCADA system, every scheduled output state change — including timestamp, tag name, and value — is recorded with a tamper-evident audit trail. This satisfies 21 CFR Part 11 §11.10(e) requirements for audit trails that capture the date and time of operator entries and actions that create, modify, or delete electronic records.
Q: For an oil and gas compressor anti-surge control application in a Class I Div 2 area, what additional components are required to install the 1756-OB16IS safely?
A: The 1756-OB16IS carries ATEX II 3G certification for Zone 2 Group IIC T4 when installed in an approved 1756-series chassis within a purged and pressurized (Type X or Type Z) enclosure per IEC 60079-2. The field-side wiring must use appropriately rated cable glands and conduit seals per NEC Article 501-15. No additional zener barriers or galvanic isolators are required on the output side, as the module’s built-in galvanic isolation provides the required separation between the hazardous-area field circuit and the safe-area backplane. Consult your local AHJ and Rockwell Automation’s 1756-UM058 installation manual for enclosure purge system sizing.
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