PROFIBUS PA

SIMATIC CFU, Field device connection

Direct interfacing of the devices in the field, especially in the hazardous area, together with the information content of the communication, are of significant importance in the process industry. PROFIBUS PA, which permits both digital data transmission and the power supply on a two-wire line with the intrinsically safe MBP transmission technology (Manchester Coded; Bus Powered) is tailored to these requirements. It is optimally suitable for direct integration of solenoid valves, sensors, and pneumatic actuators positioned in operating environments up to hazardous zone 1/21 or 0/20 into the process control system.

The typical response time of a transmitter of approx. 10 ms indicates that short cycle times can be achieved with the PROFIBUS PA. Practically all typical applications of the process industry can be implemented, both in small and large plants. Bidirectional communication and high information content allow enhanced diagnostics for fast and exact fault detection and elimination. The standardized communications services guarantee interoperability and replaceability between multi-vendor field devices and remote parameterization of the field devices during operation.

Network transition PROFIBUS PA to PROFINET

The SIMATIC Compact Field Unit (CFU) is recommended for the network transition from PROFIBUS PA to PROFINET. The CFU is changing the existing rules for field device connection and is opening up new perspectives in terms of simplicity and flexibility. The compact field distributor is installed at the process level and is connected via PROFINET directly to the process control system to form the foundation for digitalization in the field. The CFA PA variants described in the section "Network transition to PROFINET" can be used for the configuration.

Network transition PROFIBUS PA to PROFIBUS DP

The PA link is preferred as the network transition from PROFIBUS PA to PROFIBUS DP. When using the PA link, the transfer rate on the PROFIBUS DP is independent of the lower-level PROFIBUS PA segments. The configuration of the PA link depends on the fieldbus architecture. The types of coupler described in the section "Network transition to PROFIBUS PA" can be used for the configuration. With a small amount of data (small quantity framework) and low timing requirements, the DP/PA coupler can also be operated in stand-alone mode as a gateway.

The advantages of distributed field automation and the use of the PROFIBUS PA profile include low hardware overheads, cost-effective engineering, increased operational safety and problem-free maintenance. These advantages are underlined by the following features:

• Modularity and uniformity from the sensor up to the control level enable new plant designs
• Implementation of intrinsically-safe applications through use of the fieldbus in hazardous areas
• Redundant PROFIBUS PA architectures (ring and line topologies with coupler redundancy) support Flexible Modular Redundancy (FMR) from the automation system (controller) down to a PA field device
• Safety-related and fault-tolerant applications with low device and cabling requirements
• Reduced configuration costs through simple, central engineering of the field devices (PROFIBUS PA and HART with SIMATIC PDM, also cross-vendor)
• Simple installation using two-wire cable for common power supply and data transmission
• Reduced commissioning costs through simplified loop check
• Low servicing costs thanks to simple wiring and comprehensive diagnostics capabilities