You are here:
- Home
- Product
- Cables & Connectors
- Communication & Network
- Allen-Bradley 1785-PFB Profibus Communication Module
SKU: 1785-PFB
Allen-Bradley 1785-PFB Profibus Communication Module
The Allen-Bradley 1785-PFB is a Profibus DP communication module designed for the PLC-5 system. It enables 1771-based controllers to interface with Profibus networks at speeds up to 12 Mbps, supporting both Master and Slave configurations for comprehensive multi-vendor device integration.
Technical Overview
The Allen-Bradley 1785-PFB acts as a high-performance communication interface that enables PLC-5 controllers to connect directly to a Profibus DP (Decentralized Periphery) network. This module bridges the gap between Rockwell Automation’s legacy architecture and open-standard industrial fieldbus systems. By installing the 1785-PFB into a PLC-5 1771 I/O chassis, users allow the controller to function as a Profibus DP Master or Slave, facilitating seamless data exchange with a diverse range of third-party devices such as drives, sensors, and remote I/O stations.
Functional Integration and Network Management
This module manages complex network protocols by offloading communication tasks from the main PLC processor. Because the 1785-PFB handles the specific timing and cyclic data exchange requirements of the Profibus standard, it preserves the controller’s scan time for critical logic execution. Furthermore, the unit supports data rates up to 12 Mbps, which ensures high-speed synchronization across the factory floor.
To streamline system setup, the 1785-PFB utilizes a standard 9-pin D-shell sub-miniature connector for network attachment. Consequently, maintenance teams can integrate the module into existing Profibus infrastructures using standard cabling and termination techniques. Since the module fits into any single slot of a 1771 I/O rack, it offers a space-efficient solution for upgrading communication capabilities without requiring significant hardware re-engineering.
Key Technical Characteristics
- Manufacturer:Â Allen-Bradley / Rockwell Automation
- Model Identification:Â 1785-PFB
- Module Function:Â Profibus DP Master/Slave Scanner
- Platform Compatibility:Â PLC-5 Systems (1771 Chassis)
- Maximum Baud Rate:Â 12 Mbps
- Connection Port:Â 9-pin D-sub (RS-485)
- Network Capacity:Â Supports up to 125 Slave devices (in Master mode)
- Backplane Current Load:Â 1.2 A at 5V DC
- Configuration Tool:Â Typically configured via Profibus Configuration Software (Windows-based)
Primary Applications
- Connecting PLC-5 controllers to Siemens, ABB, or other third-party Profibus-compatible drives.
- Integrating non-Rockwell remote I/O into a centralized Allen-Bradley control system.
- Enabling data exchange between heterogeneous PLC platforms in multi-vendor plants.
- Modernizing legacy machinery by adding standardized fieldbus communication.
You may also like
The Allen-Bradley 1771-OW is an 8-channel electromechanical relay output module engineered for the classic PLC-5 architecture. Procure this factory-original surplus hardware in brand new condition, backed by global logistics support and rapid transit options. Contact us now to secure your technical components.
Allen-Bradley 1756-EN2T ControlLogix EtherNet/IP Communication Bridge Module
The Allen-Bradley 1756-EN2T is a Fast Ethernet communication bridge for ControlLogix networks that handles 256 Logix and 128 TCP/IP connections. This single-slot module enables 10/100 Mbps data transfers, supports CIP Safety and 8 axes of integrated motion, and integrates easily into standard 1756 chassis.
Allen-Bradley 1761-NET-AIC MicroLogix and SLC Communication Adaptor
The Allen-Bradley 1761-NET-AIC is a versatile AIC+ communication adaptor that connects DF1 devices to DH-485 networks. It provides RS-232 to RS-485 isolation and supports MicroLogix and SLC 500 controllers for robust industrial data exchange.
Allen-Bradley 1785-L40L CPU Module
The Allen-Bradley 1785-L40L is a high-performance PLC-5/40L controller featuring 48K words of memory and 2048 I/O capacity. It provides integrated DH+ and Remote I/O connectivity for robust industrial automation and legacy system support.
Allen-Bradley 1734-IE4C POINT I/O 4 Point Analog Input Module
The Allen-Bradley 1734-IE4C is a 4-channel analog current input module for POINT I/O systems. It features 16-bit resolution for 0-20mA and 4-20mA signals. This compact 1734 module offers high-density monitoring and supports removal under power for continuous operation.
Allen-Bradley 1756-SYNCH Synchlink Communication Module
The Allen-Bradley 1756-SYNCH is a ControlLogix SynchLink module providing 5 Mbps fiber-optic communication. It enables precise time synchronization and high-speed data broadcasting between multiple chassis for coordinated motion control.
Allen-Bradley 1785-ME16 PLC-5 EEPROM Memory Module
The Allen-Bradley 1785-ME16 is a 16K Word EEPROM memory module designed for the PLC-5 series. It provides non-volatile program backup and features a hardware write-protection jumper to ensure data integrity and automatic system recovery for enhanced and Ethernet PLC-5 processors.
Allen-Bradley 1771-OZL PLC-5 Digital Relay Contact Output Module
The Allen-Bradley 1771-OZL is an 8-point Digital Contact Output Module for the PLC-5 system. Utilizing hermetically sealed dry-reed relays, it provides eight Form A normally open contacts organized into four isolated groups. Rated for 0-24V AC/DC at 100mA, this module ensures high-speed switching and superior signal isolation for sensitive low-power industrial applications.
Allen-Bradley 1785-ENET/C PLC-5 Ethernet/IP Interface Module
The Allen-Bradley 1785-ENET/C is an Ethernet/IP expansion module for PLC-5 series controllers. It enables high-speed networking via Channel 3A, supports BOOTP/DHCP addressing, and provides a robust bridge between legacy processors and modern Ethernet-based automation systems.
Allen-Bradley 1756-TBCH ControlLogix 36-Pin Cage-Clamp Removable Terminal Block
The Allen-Bradley 1756-TBCH is a 36-pin cage-clamp Removable Terminal Block (RTB) for the ControlLogix system. It provides a secure, vibration-resistant interface for 1756 I/O modules, supporting 22–14 AWG wiring and ensuring fast, tool-free module replacement without disturbing field connections.
Allen-Bradley 1785-ME32 PLC-5 EEPROM Memory Module
The Allen-Bradley 1785-ME32 is a 32K-word EEPROM memory module designed for the PLC-5 series. It provides secure, non-volatile backup for control programs and device configurations, ensuring data retention during power loss and enabling easy program transfer between processors in industrial environments.
Allen-Bradley 1785-L20E PLC-5/20E Ethernet Processor Controller Module
The Allen-Bradley 1785-L20E is an enhanced PLC-5/20E processor featuring 16K memory and integrated Ethernet communication. It supports up to 512 I/O points, providing a reliable and scalable control solution for 1771-chassis industrial systems.


























