Product Description:

The 3EX450.26-2 is a communication controller produced by B & R Automation for the System 2005 Controllers series. It installs on the backplane of a System 2005 rack and serves as the central link between higher-level CPUs and distributed field devices. In a typical machine cell, it manages cyclic data exchange, forwards diagnostics, and handles startup parameters so sensors, actuators, and drives can communicate over one bus without additional gateway hardware. This arrangement keeps remote field communication tied directly to the rack-based control platform and supports orderly data transfer across the automation system.

The on-board configuration port uses an RS232 interface, allowing a computer or HMI panel to load parameter sets through standard serial cabling. For the field network, the module provides an RS422 differential pair that supports long cable runs and strong noise immunity. Its protocol layer operates as an InterBus master, so the controller initiates telegrams and manages logical ring operation for as many as 256 remote stations. Bus timing is fixed at 500 kBaud, which balances update speed with electromagnetic compatibility in industrial environments. To help prevent ground loops, the RS422 transceiver is electrically isolated, so the communication lines can float in relation to the controller logic ground without corrupting signals. Differential signaling also helps the network remain stable where nearby motors, contactors, or switching devices introduce electrical interference.

For process data handling, the board accepts up to 512 bytes of input data from the field and can transmit 512 bytes of output during each cycle. An expanded PCB service memory area stores extended diagnostics and retains error logs after power is removed. That stored information can remain available after a shutdown or restart, which helps preserve fault history within the controller. The memory area stays on the board, so operating records remain associated with the controller instead of the connected field devices.