# Real-time Ethernet Driver

The EC-Simulator stack currently supports a variety of different Real-time Ethernet Driver modules, each contained in a single library file, which is loaded by the core library dynamically.
Which library is actually loaded depends on the Link Layer parameters at runtime.

Real-time means operating directly on the register of the device set instead of using the operating system’s native driver.

The principle of the Real-time Ethernet Driver selection is that the Ethernet Driver name (Ethernet Driver identification) is used to determine the location and name of a registration function called by EC-Simulator and registers function pointers that allow access to the Real-time Ethernet Driver functional entries.

The EtherCAT® Real-time Ethernet Driver will be initialized using a Real-time Ethernet Driver specific configuration parameter set.
A pointer to this parameter set is part of EC-Simulator’s initialization settings when calling the function [`esInitSimulator()`](api_general.html.md#_CPPv415esInitSimulator10EC_T_DWORDPK25EC_T_SIMULATOR_INIT_PARMS) .

EC-Simulator supports two Real-time Ethernet Driver operating modes:

> - Interrupt mode all received Ethernet frames will be processed immediately in the context of the Real-time Ethernet Driver receiver task.
> - Polling mode, the application must cyclically call [`esExecJob()`](api_general.html.md#_CPPv49esExecJob10EC_T_DWORD13EC_T_USER_JOBP19EC_T_USER_JOB_PARMS) with job [`eUsrJob_ProcessAllRxFrames`](api_general.html.md#_CPPv4N13EC_T_USER_JOB26eUsrJob_ProcessAllRxFramesE) in order to trigger EC-Simulator to call the Real-time Ethernet Driver receiver polling function and process received frames.

#### IMPORTANT
In polling mode, the MainDevice cycle time must be at least two times higher than the simulator cycle time. E.g. if the simulator runs with 1 ms, the MainDevice cycle time must be at least 2 ms. If the Real-time Ethernet Driver is running in interrupt mode (non-standard), processing of received frames is done immediately after the frame is received.

#### NOTE
Real-time Ethernet Driver modules not listed here may be available if purchased additionally. Not all Real-time Ethernet Driver modules support interrupt mode.