Product Description:

The 3EX250.60-1 is a fieldbus master card developed by B & R Automation for the System 2005 Controllers series. Installed in a control rack, the board gives the CPU an additional serial network channel so distributed I/O stations can be integrated in real time. Within an industrial automation cell, it functions as the physical interface between the central processor and remote slaves, exchanging process data, diagnostics, and parameter sets.

The interface follows a master-slave principle, so the board initiates each transaction and remote units answer in their assigned time slot. Communication travels over RS485, and the module detects line speed through automatic recognition, eliminating manual DIP-switch settings. When connected devices support the highest bandwidth, the card transmits at 2 MBit/s, a rate suited to positioning loops. Wiring uses shielded twisted-pair conductors to minimize noise, and an external terminating resistor must be placed at the end of the trunk to limit reflections on long runs. With power consumption of 1.5 W, the card imposes little load on the backplane, and it can source an isolated 5 V / 200 mA auxiliary feed for transceivers or sensors.

Network layout follows a physical bus topology, and cabling terminates on a 9-pin D-Sub socket for connection with standard sub-D lines. One master can supervise up to 13 local I/O slice modules mounted directly beside it, while downstream repeaters and couplers expand coverage to 31 remote slaves distributed along the cable. The controller assigns each participant a dynamic address value of 99 during startup, ensuring deterministic polling order after hot swaps. Electrical energy for the board is provided through the dedicated PS465 power-supply slot, keeping its logic isolated from higher-voltage actuator feeds.