A relaying node is in bidirectional communication with at least a first and a second sendingreceiving radio node, and the relaying radio node receives at least a first signal carrying at least first data and a second signal carrying at least second data. The method comprises the following steps. The present writing implement therefore allows easy observation of the view on the opposite side of the pen element as the pen point and allows the end point of the drawn line to be readily distinguished. Further, a portion of the derivative signal including samples having lower values than the threshold is determined to correspond to a ST window for that cardiac cycle if that portion fulfills predetermined requirements. The node then monitors the port for a return signal.