The ABB AC 800F has a modular structure. The AC 800F CPU is designed as a backplane to which various modules – power supply units, Ethernet or fieldbus modules – can be attached in line with the application. On the fieldbus side, modules for PROFIBUS-DPV1, FOUNDATION Fieldbus HSE, MODBUS (master/slave, RTU or ASCII), IEC 608 0-5-101 and CAN for Freelance Rack I/O are available. The fieldbus line and the connected PROFIBUS slaves are entirely configured and parameterized using the Control Builder F engineering tool. No further external tools are needed for configuration. PROFIBUS slaves can be integrated into the system using a GSD) file or FDT/DTM). In the case of FOUNDATION Fieldbus, configuration takes place using CFF or DD files. This allows fieldbus parameterization even without connected field devices.

Also Freelance Rack I/O can be connected to the ABB AC 800F, in which case a CAN module is used. This allows you to operate five I/O racks, with a total of around 1000 I/Os, for each AC 800F. The I/O racks are equipped with a link module and up to nine I/O modules and can be mounted separately at a distance of up to 400 m from the AC 800F.

The ABB AC 800F uses the fieldbus modules to collect and process real-time and diagnostic data. Up to four fieldbus modules can be mounted into one AC 800F.

The fieldbus modules have the following tasks and
characteristics:
• Electrical isolation between the process and system
• Status LEDs for the module status
• Independent fault detection and fault signaling
• Connection of the fieldbus lines

DETAILS OF THE FIELBUS MODULES	ABB CH	ABB PLC
TYPE	CHANNELS	FUNCTION
CAN module	1	Connection of up to 5 Freelance I/O racks
Serial module		RS /RS4 /RS485 configurable for MODBUS, IEC 608 0-5-101 telecontrol protocol
PROFIBUS module	1	Full-value PROFIBUS DPV1 Master
FF-HSE module	1	For the connection of up to 10 LD 800HSE Linking Devices with 10/100 MBaud autosense twisted pair connection

Process stations and the operator and engineering level in the Freelance system communicate with each other via Ethernet.

ETHERNET MODULES FOR THE SYSTEM BUS
TYPE	CHANNELS	FUNCTION
Ethernet module	1	Twisted pair connection 10 base T for connection to hubs or switches
Ethernet module	1	BNC connection 10 base for thin coaxial cable (Cheapernet), 10 MBit/s
Ethernet module	1	AUI connection 10 base 5 and 10 base FL via coupler

The ABB AC 800F scope of functions provided by the Freelance system corresponds to the basic supply defined in IEC 61131-3, in addition to numerous other high performance, industry-proven functions and function blocks. They are accommodated in a function block library and can be supplemented by user-specific function blocks. While designing the station and during configuration, the processing capacity and speed of the process station can be easily adapted to the demands of the automation task. Program execution in the process station is based on a task-oriented, real-time multitasking operating system, leading to a flexible strategy for processing programs.
Different modes are available for task execution:

• Cyclical processing with cycle times from 5 ms upward
• Fastest-possible processing (PLC mode)

Along with the user tasks, system tasks – in which functions can also be processed – are automatically made available. These tasks are executed once in case of the following events:

• RUN
• STOP
• COLD START
• WARM START (voltage restored)
• REDUNDANCY TOGGLE
• ERROR