Product Description:

The 2ME903.99 central unit belongs to the System 2010 Controllers series from B & R Automation. As the CPU of a compact PLC platform, it hosts the real-time operating kernel, executes ladder or structured-text logic, and coordinates fieldbus communication with remote I/O and drive modules. In an industrial line, this controller governs sequence control, interlocks, and data logging to keep machines synchronized and within process tolerances. Its central role allows one module to manage logic execution, retained data, and communication tasks without requiring separate processing hardware for each function.

An onboard battery uses Lithium chemistry, and its nominal output of 3 V / 950 mAh sustains the internal clock and memory retention through power loss. Application code is stored in nonvolatile EPROM with a capacity of 1 MB, which helps preserve the program during outages and power cycling. Volatile working data resides in 256 kB of RAM, giving the CPU space for variables, buffers, and communication stacks while the system is running. A front-panel Programming LED lights when the module enters download mode, providing a clear indication that write access is active. This separation between retained memory and working memory helps the controller restart with stored application data intact while temporary operating data is rebuilt as needed.

The controller uses a User Program Memory arrangement that separates application code from diagnostic functions. It tolerates storage humidity from 0 to 95% RH without condensation, allowing warehousing in varied climates before installation. A dedicated Write Protect Switch can lock the EPROM against unintended alteration, and the switch must be disabled before parameters or stored code are changed. This added hardware control helps reduce the chance of accidental edits when the module is being handled, stored, or connected for updates.