Product Description:

The BC9191-0000 Bus Terminal Controller is manufactured by Beckhoff and belongs to the BC Bus Terminals series. It serves as a DIN-rail node that links a stack of modular I/O terminals to a higher-level fieldbus while running user logic locally. By embedding a micro PLC and the necessary communication electronics, the unit allows compact machines, conveyor sections, and HVAC panels to exchange process data with a central controller without a separate rack-mount PLC.

Configuration and communication are handled through the TwinCAT ADS protocol; the coupler therefore accepts parameter sets transmitted as a BX file and can be reached with ADS commands during commissioning. Because ADS via the fieldbus is Supported, the controller can be diagnosed or reprogrammed from any network node without a direct USB or serial link. A universal fieldbus interface is present, so the device can be ordered with the appropriate physical layer for the target system while the internal Beckhoff runtime environment executes the PLC program stored on board. Internally, a K-bus interface connects the electronic terminals so process images are transferred to the CPU each cycle, and a PLC program is present to process that image.

For persistent variables, the controller allocates 2000 bytes of retain memory housed in NOVRAM, allowing process counters or calibration data to survive power loss. Each retain block is written within 2 ms, which minimizes cycle interruptions when values change frequently. These retention features, combined with error-tolerant storage hardware, protect application data against sudden voltage dips common on factory floors. The architecture fits seamlessly into the BC Bus Terminals stack, so the same housing width and push-in contacts can be used while still offering battery-free nonvolatile storage.