Product Description:

The 3EX450.66-2 module is a communication expansion produced by B&R Automation for the System 2005 Controllers series. Mounted beside the main CPU, this part functions as the interface that turns the controller into a PROFIBUS network master, enabling centralized coordination of remote I/O racks, drives, and sensors within an industrial cell. By embedding this fieldbus capability directly in the rack, the product eliminates the need for an external gateway and shortens the control loop between the PLC task layer and distributed devices.

Service access is handled through a diagnostic channel that transmits at 9600 baud. The maintenance cable attaches to a 9-pin D-sub connector that carries a single RS-232 signal, and the lack of galvanic separation on this path means the connected computer and controller share a common reference during troubleshooting. Runtime statistics and protocol data are buffered in a dual-port RAM area sized at 2 KB; this memory is directly mapped to the host processor so no additional bus cycles are needed for status reads. An ASPC2 communication ASIC executes the protocol stack and contributes to the module's overall power requirement of 5.5 W, which must be considered when sizing the backplane supply.

The field side is isolated from logic by an opto barrier and presents an RS-485 differential channel on a second 9-pin D-sub connector. It operates as a PROFIBUS DP Master and can clock the bus anywhere from 9.6 kBd up to 12 MBd to match cable length and topology. The card can exchange up to 512 bytes of cyclic input data and the same amount of output data per scan while addressing as many as 125 subordinate stations. With the host controller supplying configuration and diagnostics through the isolated link, deterministic communication is maintained even when multiple slaves request service simultaneously.