Object Controller (OC)
An object controller is a trackside computer that connects field elements such as points, signals, level crossings and train detection to a digital interlocking over an IP network. It translates the interlocking's commands into electrical actions and reports the status of the elements back to the interlocking.
How it works
In a conventional relay interlocking, each point machine and signal is wired directly to the interlocking with dedicated copper cables. A digital interlocking replaces this with object controllers placed near the field elements. The interlocking sends commands over a data network, the object controller drives the element and monitors its position, and status messages travel back the same way.
In the EULYNX architecture, the interfaces between interlocking and object controllers are standardised: for example SCI-P for points, SCI-LS for light signals and SCI-TDS for train detection. These run over RaSTA, a safety transport protocol that protects messages against loss, reordering and corruption, so object controllers from different suppliers can work with the same interlocking.
Why it matters for security
Object controllers are the point where safety-critical field elements become network endpoints. They sit in unmanned cabinets along the line, communicate over shared IP infrastructure and are numerous, which makes them attractive both as targets and as entry points into the interlocking network.
The standardised interfaces cut integration cost but also mean an attacker who understands the protocols can apply that knowledge across many installations. Continuous monitoring of the traffic between interlocking and object controllers, including the content of commands and status messages, is how operators detect unauthorised or abnormal activity at this layer.
Related solution
Protecting interlocking systems at the core of rail safety
Deep inspection of standardized interlocking-to-field communications over IP.
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