ABB Procontic CS31 07 KR 91 Central Unit for Distributed Automation
The ABB Procontic CS31 07 KR 91 is a central processing unit for the CS31 intelligent distributed automation system. This central unit serves as the main controller for the distributed architecture, executing user programs, managing data exchange with remote I/O units, and handling communication across the RS485 twisted pair bus. The CS31 system simplifies industrial control wiring and implementation through decentralized architecture, reducing installation costs by up to 80% compared to traditional centralized control systems. The 07 KR 91 is suitable for applications with high modularity requirements and cost sensitivity, including manufacturing automation, material handling systems, and industrial process control.
Product Specifications
Product Line: ABB Procontic CS31 Intelligent Distributed Automation System
Model: 07 KR 91 Central Unit
Program Memory: 7K FLASH EPROM
Digital Inputs: 20 channels of 24V DC input
Digital Outputs: 12 channels of relay output
Advanced Functions: PID control support
Power Supply Options: 24V DC, 115V AC, 230V AC
Communication: RS485 twisted pair bus
System Architecture: Distributed automation with remote I/O units
Distributed Automation Architecture
The CS31 system is a distributed automation platform that simplifies industrial control through decentralized architecture. The system consists of a central processing unit installed in a control cabinet, with remote input/output units positioned near sensors and actuators throughout the facility. These remote units connect to the central unit via an RS485 twisted pair bus, reducing the length of individual sensor and actuator wiring runs. This distributed architecture can reduce wiring costs by up to 80% compared to traditional centralized systems, where every sensor and actuator wire must run directly to the central controller. The architecture also simplifies system expansion and modification, as new remote units can be added without running extensive new cable bundles.
Central Unit Functions
The 07 KR 91 serves as the central processing unit for the CS31 system, executing user programs that control the automation process. The central unit coordinates all system activities, managing data exchange with remote I/O modules and handling communication with supervisory systems. The central unit stores the user program in 7K FLASH EPROM memory, providing non-volatile storage that retains program data during power interruptions. The central unit processes inputs from remote I/O units, executes control logic based on the user program, and sends output commands to remote units to control field devices. The central unit also handles system diagnostics, monitoring communication with remote units and reporting faults to operators.
Built-in I/O Capabilities
The 07 KR 91 includes built-in I/O capability, providing 20 channels of 24V DC digital input and 12 channels of relay output. These built-in I/O points allow the central unit to directly connect to local sensors and actuators without requiring remote I/O units for small-scale applications. The digital inputs accept signals from pushbuttons, limit switches, proximity sensors, and other 24V DC field devices. The relay outputs provide isolation between the controller and field devices, with contact ratings suitable for driving contactors, solenoids, indicator lamps, and other industrial loads. The combination of built-in I/O and remote I/O support provides flexible system configuration from small standalone controllers to large distributed systems.
Advanced Control Functions
The 07 KR 91 supports advanced control functions including PID (Proportional-Integral-Derivative) control for process regulation applications. PID control loops allow the central unit to maintain process variables such as temperature, pressure, flow, or level at desired setpoints by modulating control outputs based on feedback from sensors. The PID function is essential for applications requiring precise regulation, such as temperature control in plastic processing, pressure control in hydraulic systems, and flow control in water treatment. The central unit's PID capabilities eliminate the need for external process controllers, reducing system complexity and cost.
Power Supply Options
The 07 KR 91 is available with multiple power supply options to accommodate different facility power configurations. The 24V DC option is suitable for control systems with existing DC power supplies, common in electronics manufacturing and automotive assembly applications. The 115V AC option provides compatibility with North American facility power. The 230V AC option accommodates European and other international power systems. The power supply flexibility simplifies system integration, allowing the central unit to be powered directly from available facility power without requiring additional power conversion equipment.
CS31 Protocol and Communication
The CS31 system uses a proprietary communication protocol that supports up to 31 logical bus modules for bus communication. Each device on the CS31 bus allocates at least one CS31 module, with additional modules allocated when S500 I/O modules are used. The protocol supports both digital and analog data exchange between the central unit and remote I/O units. CS31 software modules can occupy a maximum of 15 bytes of inputs and 15 bytes of outputs in the digital area, corresponding to 120 digital inputs and 120 outputs. In the analog area, each CS31 software module can allocate up to 8 words of inputs and 8 words of outputs. Up to 31 CS31 software modules can be connected to the CS31 bus, providing substantial I/O capacity for large distributed systems.
Remote I/O Unit Compatibility
The 07 KR 91 central unit communicates with a range of remote I/O units from ABB's CS31 product family. Binary input units such as ICSI 08 D1 provide 8-channel 24V DC non-isolated inputs, while ICSI 16 E1 offers 16-channel isolated inputs with configurable input delay. Binary output units include ICSO 08 R1 with 8-way relay output, and ICSO 16 N1 with 16-way transistor output and short-circuit protection. Hybrid I/O units such as ICSK 20 F1 provide combined 12 inputs and 8 relay outputs. IP65 protected units including ICPI 16 D1 and ICPO 16 H1 are available for harsh environments. Analog units include ICSE 08 A6 with 8 voltage/current channels, ICST 08 A8 with 8 PT100 temperature channels, and ICSA 04 B5 with 4 voltage/current output channels. This comprehensive range of I/O units allows system configuration for diverse application requirements.
System Configuration and Addressing
CS31 devices are configured and addressed using ABB's engineering software. The central unit and remote I/O units are assigned module addresses using rotary switches on the devices, with address ranges from 0 to 61. When configuring the CS31 bus, each device is added to the PLC configuration below the CS31_Bus node in the software. The module address must match the value set on the device's rotary switch. For devices with more than 15 bytes or 8 words of inputs or outputs, multiple CS31 software modules are allocated automatically. CS31 devices can internally manage up to 2 CS31 software modules in the digital area (240 digital inputs and 240 digital outputs) and up to 5 CS31 software modules in the analog area (40 analog inputs and 40 analog outputs). This addressing scheme provides systematic organization for large distributed systems.
Diagnostic Capabilities
The CS31 system includes powerful diagnostic capabilities for system monitoring and troubleshooting. The distributed architecture supports online expansion units, allowing I/O points to be added without system shutdown in many cases. Remote I/O channels can be programmed like centralized devices, simplifying the programming model for distributed systems. The central unit monitors communication status with all remote I/O units, detecting faults such as broken communication links or failed units. Diagnostic information is available to the user program for automatic fault handling and to maintenance personnel for system troubleshooting. These diagnostic capabilities reduce downtime by enabling rapid identification and resolution of system faults.
Industrial Applications
The ABB Procontic CS31 system with 07 KR 91 central unit is deployed across diverse industrial automation applications. In manufacturing automation, it controls assembly lines, material handling systems, and packaging equipment. In process industries, it manages batch processes, material transfer systems, and equipment interlocking. In building automation, it controls HVAC systems, lighting, and access control across large facilities. The distributed architecture is particularly advantageous for applications where sensors and actuators are spread across large areas, such as conveyor systems, material storage facilities, and building management systems.
Conclusion
The ABB Procontic CS31 07 KR 91 central unit provides distributed automation capabilities with built-in I/O, remote I/O support, and RS485 bus communication. Its flexible configuration, diagnostic capabilities, and PID support make it a versatile solution for industrial automation applications requiring cost-effective distributed control.
