Pilz PSS Series Operating Manual page 33

If there is a short circuit on SafetyBUS p between CAN_H and CAN_L, the
measured curve will deviate from the typical curve: a step is visible within
the measured curve. On long bus lines, you will need to enlarge the view to
make the step visible.
You can establish the location of the short circuit from this step. To do this,
the cursor must be positioned on the rising edge of the step.
Fig. 5-9: Cursor position to determine the location of a short circuit
The measured curve also shows if a terminating resistor was not removed
when the measurement was made: the measured curve is constant over
the whole measuring range of 6.7 km.
Fig. 5-10: Measured curve when terminating resistor is not removed
Operating Manual: PSS SB TESTER
Cursor
Step
5-15