====== Writing a new interface for a new EtherCAT slave ======
===== Hints =====

  * You can use ''EtherCatInterfaceElmo'' as an example.
  * Your interface has to inherit from ''EtherCATInterfaceBase''.
  * The most basic implementation only includes the low level functions ('ll_'-prefix)
  * A method like ''int64_t getPosition()'' is recommended to avoid overflow problems (see below)


===== int64_t getPosition() =====
The position is often sent as a 32 bit signed integer (~4*e+9 different values).
With a high-resolution encoder, this value can easily overflow.

To avoid this problem use a method implementation like this:
<code>
int64_t EtherCATInterfaceElmo::getPosition(int driveNumber)
{
	int32_t rawPos = ll_getPositionActualValue(driveNumber);
	int32_t diff = rawPos - drives[driveNumber].prevRawPos;
	drives[driveNumber].prevRawPos = rawPos;
	drives[driveNumber].absPos += static_cast<int64_t>(diff);
 	return drives[driveNumber].absPos + static_cast<int64_t>(drives[driveNumber].posOffset);
}
</code>