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6 FUNCTIONAL SAFETY
6.4 Safety sub-function
■Diagnosis with test pulses
• Test pulse diagnosis function
When the output signal of the CN8-6/CN8-7 pin is on, off-pulses are output periodically to diagnose wiring abnormalities.
The following shows the operation sequence when STOS (STO output) is assigned to the output signal of the CN8-6/CN8-7
pin. When STOS (STO output) is on, off-pulses are output to the CN8-6/CN8-7 pin periodically. Off-pulses are output from the
CN8-6 pin and CN8-7 pin at different timings. The width of the off-pulses can be set with [Pr. PSD30 Output device - Test
pulse off time]. Set the off-pulse width so that external devices are not affected by the output of off-pulses.
If an error is detected by the test pulse diagnosis, [AL. 556 Output device diagnosis error (safety sub-function)] occurs.
Whether or not to perform diagnosis on output devices using test pulses can be selected with [Pr. PSD29 Output device - Test
pulse diagnosis execution selection].
• Setting functional safety parameters
For the output devices that are assigned with [Pr. PSD08 Output device selection DO1], set the following parameters.
Set whether to execute test pulse diagnosis in [Pr. PSD29 Output device - Test pulse diagnosis execution selection]. Set the
off time of the test pulses output from the output device in [Pr. PSD30 Output device - Test pulse off time].
The achievable safety level is influenced by the devices used and the setting of this functional safety parameter. Refer to the
following for details.
Page 433 Achievable safety level
Parameter Name
PSD29 Output device - Test pulse diagnosis execution selection
PSD30 Output device - Test pulse off time
ON
OFF
ON
OFF
ON
OFF
STOS (STO output)
Safety output device test pulse off time
Safety output device test pulse off time
CN8-6 pin
CN8-7 pin
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