Beckhoff AX8911, Документация

Страница: 29 / 65

Use of the STO function
AX8911 29 Version: 1.2.0
6 Use of the STO function
CAUTION
Restart lock
The restart lock is to be implemented in the higher-level safety controller.
Alternatively, this can be adapted by the user or the machine manufacturer by modifying the fail-safe pro-
gram on the AX8911.
CAUTION
OSSD signals on X15 and X25
The test pulses must not exceed a length of 3.5 ms. Longer test pulses can lead to triggering of the STO.
Alternatively, this can be adapted by the user or the machine manufacturer by modifying the fail-safe pro-
gram on the AX8911.
CAUTION
Cross-circuits / external power supply
The higher-level safety controller is responsible for checking the wiring between the safety controller and
the TwinSAFE inputs of the AX8911 (X15, X25). The necessary tests and checks arise from the risk and
hazard analysis carried out by the machine manufacturer.
NOTE
Testing the X15 and X25 inputs
The functions of the STO inputs 1 and 2 of the connections X15 or X25 are tested internally by the AX8911
TwinSAFE Drive Option card. The external test pulses for detecting cross-circuits or an external power sup-
ply serve only to check the correct wiring between the safety controller and the TwinSAFE Drive Option
card.
Using the STO inputs with TwinSAFE outputs
In this use case the STO inputs 1 and 2 of the digital inputs X15 and, if applicable, X25 are wired directly to
safe outputs, for example of an EL2904. When using the EL2904, the safe outputs are parameterized in
such a way that the test pulses are active, but the parameter
Current Measurement active is disabled. If
other TwinSAFE outputs are used they must also be parameterized in the same way so that test pulses are
active at the output.
A filter is implemented within the logic of the AX8911 (default 3.5 ms) so that the test pulses of, for example,
the EL2904 cannot lead to a switch-off of the STO channels.