Product Overview and Multi-Protocol Integration

The SST-PFB-CLX (SSTPFBCLX) is a high-performance PROFIBUS DP Master/Scanner module engineered to integrate PROFIBUS field devices directly into the Allen-Bradley ControlLogix platform. Developed by SST (a Molex company), this module acts as a seamless communication bridge, allowing ControlLogix processors to control and monitor PROFIBUS-compliant instruments, drives, and I/O blocks as if they were native EtherNet/IP devices. By utilizing the SST-PFB-CLX, engineers can leverage the vast ecosystem of PROFIBUS hardware—prevalent in European and specialized process industries—while maintaining the centralized control and diagnostic power of the Rockwell Automation Integrated Architecture.

Hardware Architecture and Data Processing

The SST-PFB-CLX occupies a single slot in any standard 1756 ControlLogix chassis. It is designed for high-speed data exchange, utilizing an onboard processor to manage the PROFIBUS cycle independently of the PLC scan.

• Master/Slave Versatility: The module can function as a DPV0/DPV1 Master (controlling up to 125 slaves) or simultaneously act as a DP Slave to another master, providing ultimate flexibility in complex hierarchical networks.

• High-Speed Execution: Supports all standard PROFIBUS baud rates up to 12 Mbps, ensuring deterministic performance for high-speed motion or synchronized process loops.

• Large Data Capacity: Capable of mapping up to 244 bytes of Input and 244 bytes of Output data per slave device into the ControlLogix controller tags.

• CommDTM Support: Supports FDT/DTM technology, allowing for remote asset management and configuration of field instruments (like flowmeters or transmitters) directly through the backplane.

Technical Specifications

Integrated Technical FAQ

How do I configure the PROFIBUS network for this module?

Configuration is typically performed using the SST Console software. You import the GSD files for your slave devices, define the network parameters, and download the configuration to the module via the ControlLogix backplane or the module's front-panel port.

Does the SST-PFB-CLX support "Hot Swapping"?

Yes. As a member of the 1756 family, it supports Removal and Insertion Under Power (RIUP). However, removing the module will result in an immediate loss of communication to all 125 PROFIBUS slaves, so the system should be in a safe state before removal.

Can this module handle Acyclic messaging (DP-V1)?

Absolutely. The module supports DP-V1 Acyclic read/write operations. This is essential for changing parameters on-the-fly or performing deep diagnostics on smart instruments without interrupting the cyclic I/O data.

Engineering & Installation Protocols

• Termination and Impedance: Ensure that the PROFIBUS network is correctly terminated at both physical ends of the segment. Use standard PROFIBUS connectors with built-in terminating resistors. Setting the termination switch to "ON" at the SST-PFB-CLX (if it is an end node) is critical for preventing signal reflections.

• Cabling Integrity: Use only Purple Type A PROFIBUS cable. Maintain a minimum distance of 20 cm from high-power AC lines to prevent Electromagnetic Interference (EMI) from corrupting the 12 Mbps data stream.

• Addressing Logic: Each slave on the PROFIBUS network must have a unique address (1 to 125). Avoid using address 0 (often reserved for programming tools) or address 126 (factory default for many new devices).

Engineering Advantages

The SST-PFB-CLX stands out for its diagnostic transparency. It provides a dedicated status register within the ControlLogix tag database that gives real-time health data for every slave on the network. This allows maintenance teams to identify a failed sensor or a broken cable segment instantly through the HMI, without needing to open the control cabinet. By decoupling the PROFIBUS timing from the PLC scan, the module ensures that the network remains stable even if the ControlLogix processor is under heavy computational load, making it a "set-and-forget" solution for hybrid protocol environments.