Description
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Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Allen-Bradley / Rockwell Automation |
| Catalog Number | 1746-OB32 |
| Product Family | SLC 500 |
| Product Type | Digital DC output module |
| Number of Outputs | 32 |
| Output Type | Transistor, sourcing |
| Voltage Category | 24 V DC |
| Operating Voltage | 5–50 V DC source |
| Points per Common | 16 |
| Backplane Current | 0.190 A at 5 V DC |
| Backplane 24 V Current | 0 A |
| Isolation from Backplane | 1500 V AC for 1 minute |
| Signal Delay | 0.1 ms ON / 1.0 ms OFF maximum |
| Minimum Load Current | 1 mA |
| Maximum Continuous Current/Point | 0.5 A at 30°C; 0.25 A at 60°C |
| Maximum Continuous Current/Module | 8 A |
| Maximum Continuous Current/Common | 4 A |
| Maximum Current/Common Pin | 2 A |
| Maximum On-State Voltage Drop | 1.2 V at 0.5 A |
| Surge Current | 1 A for 10 ms |
| Operating Temperature | 0 to 60°C |
| Country of Origin | Malaysia |
| Lifecycle | Discontinued |
| Warranty | 12 months |
The official Rockwell technical documentation specifies a 5–50 V DC sourcing output range, 32 outputs, 16 points per common, 0.190 A backplane consumption at 5 V, and 1500 V AC isolation from the backplane for one minute.
For Series D units, the documentation specifies a maximum continuous current of 0.5 A per point at 30°C and 0.25 A at 60°C. The maximum module current is 8 A, with 4 A per common when the appropriate VDC connections are used.
Product Introduction — Anti-Template
The Allen-Bradley 1746-OB32 is built for applications where an SLC 500 controller needs a relatively high number of discrete DC outputs in a compact I/O configuration. Its 32 sourcing channels can control field devices across two 16-point common groups, making it useful for machine sequencing, motor-control interlocks, valve solenoids, contactors, annunciators, and other discrete control functions.
One detail is easy to miss when replacing an old SLC module: 1746-OB32 and 1746-OB32E are not the same module. The OB32E adds electronic protection and uses a different operating-voltage specification. Match the exact catalog number and series before installation.
1746-OB32
1746-OB32
1746-OB32
1746-OB32
QC, Procurement & Logistics SOP
1) Inbound Verification
Verify the following before quotation and shipment:
- Manufacturer: Allen-Bradley / Rockwell Automation.
- Catalog number: 1746-OB32.
- Series/revision marking.
- Front label and catalog number.
- Terminal block condition.
- Terminal screws and wiring points.
- Backplane connector condition.
- PCB condition.
- Signs of corrosion, overheating, contamination, or previous repair.
- Exact series revision where applicable.
For used or surplus units, photograph the catalog label and terminal side. This helps the buyer confirm that the replacement matches the installed SLC configuration.
2) Functional and Live Testing
Where the correct SLC 500 test rack is available, testing may include:
- Visual inspection.
- Backplane-contact inspection.
- Controlled rack power-up.
- Module recognition by the SLC system.
- Output LED verification.
- Point-by-point output switching.
- DC load simulation.
- Measurement of output voltage under load.
- Verification of common-group wiring.
- Check for abnormal leakage or voltage drop.
- Verification of output behavior after repeated switching.
For a sourcing output module, the test fixture must provide the appropriate DC common and load arrangement. Do not test the outputs by randomly applying voltage to terminal points.
3) QA, ESD Protection, and Packaging
Before shipment, record:
- Catalog number.
- Series marking.
- Serial or manufacturing information, if present.
- Front and rear photographs.
- Terminal condition.
- Backplane connector condition.
- Functional-test results.
Use an ESD-safe bag, terminal protection, anti-impact cushioning, and a rigid carton. The terminal block should not be allowed to bear the weight of the module during shipping.
4) Global Logistics and Export Compliance
For international shipments, confirm:
- Complete manufacturer and catalog number.
- Product description: SLC 500 32-point DC sourcing output module.
- Quantity.
- Country of origin.
- Declared value and currency.
- Consignee information.
- Certificate of origin requirements.
- Warranty or inspection documentation.
- Destination import requirements.
- Express courier, air freight, or sea freight.
Rockwell identifies the country of origin for this catalog number as Malaysia. The actual product label should still be checked before preparing final export documentation.
HS classification should be confirmed according to the actual construction and customs requirements of the exporting and importing countries.
5) Secure Air and Sea Packaging
For express air shipment, protect the terminal block and backplane connector from impact and prevent movement inside the carton.
For sea freight or extended storage, use a moisture barrier and desiccant. Avoid stacking heavy materials directly on top of the module.
Technical Pitfalls & Integration Warnings
Sourcing vs. Sinking Output
The 1746-OB32 is a sourcing DC output module. Do not substitute it with the 1746-OV32, which is a sinking output module. Their field-wiring arrangements are different.
Do Not Confuse OB32 With OB32E
The 1746-OB32E is electronically protected and has a 10–30 V DC sourcing specification. The standard 1746- is specified for 5–50 V DC sourcing operation. These are separate catalog numbers and should not be treated as interchangeable without checking the application.
Check the Series Revision
The technical documentation distinguishes Series D from earlier Series A/B/C versions. Earlier versions used non-replaceable fuses for common protection, while Series D modules have a different protection/current arrangement. Confirm the actual series before using historical specifications.
Observe Common-Group Current Limits
The 32 outputs are divided into two 16-point common groups. The maximum current per common and per common pin must be respected. For Series D, the documentation specifies 4 A per common and 2 A per common pin.
Protect Inductive Loads
When switching 24 V DC inductive loads such as solenoids and relay coils, appropriate surge suppression should be used. Rockwell’s technical documentation specifically discusses suppression for inductive DC loads.
Verify the SLC Chassis and Configuration
The 1746- is an SLC 500 I/O module and must be installed in a compatible SLC architecture. Verify the chassis, processor, slot configuration, wiring, and controller program before commissioning.
Discontinued Does Not Mean Interchangeable
Rockwell lists the 1746- as discontinued since November 24, 2022. When sourcing a replacement today, the exact catalog number, series, condition, and any proposed engineering replacement should be checked rather than assuming that a visually similar modern module is a drop-in replacement.
Frequently Asked Questions
What is Allen-Bradley 1746-?
It is a 32-point digital DC sourcing output module for the Allen-Bradley SLC 500 programmable controller family.
How many outputs does the 1746- have?
It provides 32 DC transistor outputs, arranged as two groups of 16 points.
Is 1746- a sourcing or sinking module?
It is a sourcing DC output module. The corresponding sinking 32-point model is the 1746-OV32.
What voltage can the 1746- output?
The specified operating range is 5–50 V DC source. The actual load voltage and current must remain within the module’s electrical limits.
What is the maximum output current?
The maximum continuous current is 0.5 A per point at 30°C, decreasing to 0.25 A per point at 60°C. The maximum continuous module current is 8 A.
Is 1746- the same as 1746-OB32E?
No. The OB32E is an electronically protected version with a different voltage specification. Do not substitute one for the other without checking the application and system documentation.
Is the 1746- still manufactured?
Rockwell Automation lists the 1746- as discontinued on November 24, 2022. It is therefore commonly relevant to legacy-system maintenance and replacement-stock procurement.
What information should I provide when requesting a replacement?
Please provide the complete catalog number, series marking, a photo of the front label, and the existing SLC chassis/slot information. If possible, include a photo of the terminal wiring so the sourcing arrangement can be checked before shipment.
