Allen-Bradley 1756-OB32/A – 32-Point 10–31V DC Source Output Module | ControlLogix Platform
Engineering Background
The 1756-OB32/A is a high-density sourcing DC output module designed for Rockwell Automation’s ControlLogix 1756 chassis platform. Series A represents the baseline production release, engineered for deterministic, high-cycle discrete output control in demanding industrial environments. With 32 individually fused output points operating at 10–31V DC, this module delivers the channel density and electrical isolation required for large-scale machine control, process automation, and safety-adjacent applications.
Product Positioning
Targeted at OEM machine builders, system integrators, and plant engineers who require proven, catalog-standard I/O within an existing ControlLogix architecture. The 1756-OB32/A is a direct-replacement, drop-in module compatible with all 1756 chassis sizes and ControlLogix/GuardLogix controllers. Konmask.com supplies verified surplus and new-surplus units with full traceability documentation.
Complete Technical Specifications
| Parameter | Specification |
|---|---|
| Catalog Number | 1756-OB32/A |
| Series | A |
| Platform | ControlLogix 1756 |
| Module Type | Discrete DC Output (Source) |
| Number of Output Points | 32 |
| Output Voltage Range | 10–31V DC |
| Output Current per Point | 1 A continuous |
| Output Current per Module | 16 A max (all points ON) |
| Output Type | Sourcing (PNP) |
| Isolation | Group isolated (2 groups of 16 points) |
| Backplane Current (5V DC) | 120 mA |
| Backplane Current (24V DC) | 3 mA |
| Field Power Required | External 10–31V DC supply |
| Wiring System | Removable terminal block (RTB), 40-pin |
| Connector Type | 1756-TBCH or 1756-TBS6H (sold separately) |
| Dimensions (H × W × D) | 94.0 × 94.5 × 58.4 mm (3.70 × 3.72 × 2.30 in) |
| Weight | Approx. 300 g |
| Operating Temperature | 0–60 °C (32–140 °F) |
| Storage Temperature | -40–85 °C (-40–185 °F) |
| Relative Humidity | 5–95% non-condensing |
| Certifications | UL, CE, C-Tick, ATEX (Zone 2) |
| Firmware | Configurable via RSLogix 5000 / Studio 5000 |
Proven Application Environments
- Automotive Assembly Lines – High-cycle solenoid valve and actuator control with deterministic scan-time performance
- Packaging Machinery – Coordinated multi-axis discrete output sequencing for conveyors, pushers, and diverters
- Oil & Gas Processing – Reliable field-side switching in Zone 2 classified areas (ATEX rated)
- Water & Wastewater Treatment – Pump and valve control in continuous-duty, high-humidity environments
- Food & Beverage – Washdown-adjacent panel installations requiring robust DC output density
- Semiconductor Fabrication – Precision discrete control integrated with ControlLogix motion and process controllers
Engineering Advantages
- 32-Point Density – Maximizes chassis slot utilization; reduces BOM cost versus multiple lower-density modules
- Group Isolation – Two isolated groups of 16 allow mixed field-supply voltages within a single module
- Sourcing (PNP) Architecture – Compatible with the majority of industrial sensors and actuators in Asian and European markets
- Hot-Swap Capable – Module can be inserted/removed under power without chassis shutdown (ControlLogix architecture)
- Diagnostic Feedback – Per-point fault detection reported to controller tag database for predictive maintenance integration
- Removable Terminal Block – Field wiring remains intact during module replacement, minimizing MTTR
- Studio 5000 / RSLogix 5000 Native – Zero-configuration add-on; auto-detected by Logix controller upon insertion
System Architecture & Signal Flow
The 1756-OB32/A resides in any slot of a 1756 chassis and communicates over the ControlLogix backplane at full backplane bandwidth. The controller writes output data to the module’s output image table each scan. The module’s ASIC latches the output state and drives the field-side transistors accordingly. Field power (10–31V DC) is supplied externally via the RTB; the backplane supplies only logic power (5V DC, 120 mA). Each output group shares a common field power terminal, enabling dual-supply configurations for redundant field power architectures.
Signal path: Controller Output Tag → Backplane Output Image → Module ASIC → Field Transistor → Load Device
Sourcing & Quality Verification
- All units sourced from authorized distributors, OEM decommissions, or verified surplus channels
- Pre-shipment inspection: visual, label verification (catalog number, series, firmware rev), and functional power-on test
- Firmware revision and series letter confirmed against Rockwell Automation product change notices (PCNs)
- Anti-counterfeit checks: holographic label, PCB marking, and housing geometry verification
- Packaging: ESD-safe bag, foam-lined carton, humidity indicator card
- Documentation available: test report, original Rockwell datasheet, certificate of conformance upon request
Procurement Process
- Confirm Requirement – Verify catalog number (1756-OB32/A), series (A), and required quantity with your engineering team
- Request Quote – Contact Konmask via [email protected] or +0086 19859288691 for volume pricing and lead time
- Order Placement – Purchase order accepted; proforma invoice issued within 1 business day
- Quality Inspection – Pre-shipment inspection report provided before dispatch
- Shipping – DHL / FedEx / SF Express; tracking number provided; export documentation (commercial invoice, packing list) included
- After-Sales Support – 12-month warranty on verified units; technical support available via email
Technical FAQ
Q: Is the 1756-OB32/A compatible with GuardLogix controllers?
A: Yes. The module is compatible with all ControlLogix-family controllers including GuardLogix 1756-L6xS and 1756-L8xES, though it is not a safety-rated module and cannot be used in the safety task I/O tree.
Q: What is the difference between Series A and later series?
A: Series A is the original production release. Later series (B, C) may incorporate minor PCB revisions or component substitutions per Rockwell PCNs. Functionally and electrically, all series are interchangeable for standard applications.
Q: Can I mix 10V DC and 24V DC field devices on the same module?
A: Yes, within the group isolation constraint. Group 1 (points 0–15) and Group 2 (points 16–31) each have independent field power commons, allowing different supply voltages per group.
Q: Does this module require a specific RTB (terminal block)?
A: Yes. The 1756-OB32/A requires a 40-pin RTB: either 1756-TBCH (cage clamp) or 1756-TBS6H (screw clamp). RTBs are not included and must be ordered separately.
Q: What is the maximum inrush current per output point?
A: The module is rated for 1 A continuous per point. Inrush-heavy loads (e.g., lamps, capacitive loads) should be evaluated against the module’s electronic fuse trip characteristics per publication 1756-TD001.
Q: Do you provide a certificate of conformance?
A: Yes. A certificate of conformance and pre-shipment inspection report are available upon request for all orders.
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