Pilz PSS Series Operating Manual page 26

Tests/Measurements
If voltage is present at "Vcc", the test will not be carried out because the
test results could be corrupted or the Tester could be damaged.
NOTICE
While the screening test is in progess, no voltage must be supplied to the
"Vcc" pin and SafetyBUS p must not be switched on, otherwise there is the
risk of the test results being corrupted or the Tester being damaged.
When the test is complete, three pieces of information are displayed: the
limit value, the measured value and the result.
The limit value of 200 Ω is pre-assigned. If the value measured at the
resistor is greater than or equal to the limit value, an open circuit is
detected.
Example: limit value 200 Ω
5-8
measured value 10 Ω
result: no open circuit
Operating Manual: PSS SB TESTER