Allen-Bradley 1791D-0B8P – 8-Point Digital Output Expansion Module | DeviceNet Block I/O Platform
Engineering Background
The Allen-Bradley 1791D-0B8P is a discrete output expansion module designed for the ArmorBlock Guard I/O and 1791D DeviceNet Block I/O platform. It extends the digital output capacity of a DeviceNet node without requiring an additional network address, making it the preferred solution for machine builders and system integrators who need compact, distributed I/O in space-constrained panel or field-mount environments.
Product Positioning
Targeted at OEM machine builders, process automation engineers, and MRO procurement teams operating Allen-Bradley DeviceNet architectures, the 1791D-0B8P delivers deterministic output control with IP67-rated field durability. It is a direct expansion companion to the 1791D base modules and is fully compatible with Rockwell Automation’s RSNetWorx for DeviceNet configuration environment.
Complete Technical Specifications
| Catalog Number | 1791D-0B8P |
| Manufacturer | Allen-Bradley / Rockwell Automation |
| Series / Platform | 1791D DeviceNet Block I/O |
| Module Type | Expansion Digital Output Module |
| Number of Outputs | 8 × PNP (sourcing) digital outputs |
| Output Voltage Range | 10–28.8 V DC |
| Output Current per Point | 0.5 A continuous |
| Total Module Output Current | 4 A max |
| Network Interface | DeviceNet (expansion — no independent node address) |
| Connection to Base | Side-mount expansion connector to 1791D base module |
| Enclosure Rating | IP67 / NEMA 6 |
| Operating Temperature | -20 °C to +55 °C |
| Storage Temperature | -40 °C to +85 °C |
| Relative Humidity | 5–95% non-condensing |
| Shock Rating | 30 g, 11 ms half-sine |
| Vibration Rating | 5–2000 Hz, 5 g |
| Power Consumption | Supplied via base module backplane |
| Wiring | M12 micro-style connectors (8-pin) |
| Weight | 180 g (approx.) |
| Agency Certifications | UL, CE, C-Tick |
| Compatible Base Modules | 1791D-8B8P, 1791D-16B0, 1791D-0B16P and other 1791D series bases |
Proven Application Environments
- Automotive assembly lines — high-cycle solenoid valve and actuator control in wash-down zones
- Food & beverage processing — IP67 rating withstands CIP cleaning cycles and moisture ingress
- Material handling & conveyor systems — distributed output nodes reduce panel wiring complexity
- Packaging machinery — deterministic DeviceNet scan cycle supports precise motion sequencing
- Intralogistics & AGV stations — compact form factor integrates directly at the machine frame
- Water/wastewater treatment — NEMA 6 enclosure suitable for submersion-risk environments
Engineering Advantages
- Zero additional node address — expansion modules share the base module’s DeviceNet MAC ID, preserving network address space on large topologies
- IP67 field-mount design — eliminates the need for a sealed enclosure cabinet, reducing BOM cost and installation time
- PNP sourcing outputs — compatible with the majority of European and Asian sensor/actuator standards
- M12 micro connectors — tool-free field wiring with positive locking; reduces commissioning errors
- Short-circuit & overload protection — per-point electronic protection prevents cascade failures
- Status LED per output — local diagnostics without laptop or HMI connection
- Side-mount expansion — modular stack architecture allows output capacity to scale without rewiring the base
System Architecture & Signal Flow
The 1791D-0B8P attaches directly to the right side of a compatible 1791D base module via the integrated expansion connector. The base module handles all DeviceNet communication (MAC ID assignment, I/O polling, explicit messaging) and passes output data to the expansion module through the internal backplane bus. The PLC controller (e.g., ControlLogix, CompactLogix, or MicroLogix with DeviceNet scanner) maps the 8 output bits into the base module’s output assembly object. No separate EDS file or node configuration is required for the expansion module itself — it is auto-detected by the base during power-up.
Typical signal path: PLC Scanner → DeviceNet cable → 1791D Base Module → Internal backplane → 1791D-0B8P → M12 output connectors → Field actuators/solenoids
Sourcing & Quality Verification
- Origin: Genuine Allen-Bradley / Rockwell Automation manufactured component
- Stock condition: Surplus new or tested-good refurbished; condition specified at time of quotation
- Inspection protocol: Visual inspection, label verification, functional power-on test where applicable
- Traceability: Catalog number, series letter, and firmware revision documented per unit
- Packaging: Anti-static bag + foam-lined carton; original Rockwell packaging where available
- Warranty: 12-month Konmask operational warranty against manufacturing defects
Procurement Process
- Confirm compatibility — verify your 1791D base module catalog number and expansion slot availability
- Request a quote — contact support@konmask.com for volume pricing, lead time, and stock condition confirmation
- Place order — purchase order accepted via email; proforma invoice issued within 1 business day
- Inspection & dispatch — unit inspected, photographed, and shipped with tracking within 2–3 business days
- Delivery & commissioning support — Konmask technical team available for post-delivery integration questions
Technical FAQ
Q: Can the 1791D-0B8P operate as a standalone DeviceNet node?
A: No. It is an expansion-only module and must be physically connected to a compatible 1791D base module. It does not have an independent DeviceNet port or MAC ID.
Q: How many 1791D-0B8P modules can be stacked on a single base?
A: Up to two expansion modules (one input, one output, or two of the same type depending on base model) can be attached. Refer to the 1791D User Manual (Pub. 1791D-UM001) for your specific base module’s expansion rules.
Q: Are the outputs short-circuit protected?
A: Yes. Each output point includes electronic short-circuit and overload protection. A fault condition is reported back to the controller via the DeviceNet I/O status bits.
Q: What is the maximum cable length for the M12 output connectors?
A: Rockwell recommends a maximum of 6 m (20 ft) for the drop cables from the module to the actuator to maintain signal integrity and voltage drop within specification.
Q: Is this module compatible with Studio 5000 / Logix Designer?
A: Yes, when used with a DeviceNet scanner module (e.g., 1756-DNB or 1769-SDN) in a Logix-based system. The base module’s EDS file covers the expansion module’s I/O mapping.
Q: What is the difference between 1791D-0B8P and 1791D-0B8?
A: The “P” suffix denotes M12 micro-style (pico) connectors. The non-P variant uses a different connector style. Verify your existing wiring harness before ordering.
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