Acknowledging Faults; Ramp Monitoring - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
Safety notes and instructions
Parameterizing V_MAX and T_RAMP must be selected so when it is identified
that the permissible travel range has been exited, and with the resulting stop re-
sponse, when STO is initiated, the axis can always be braked to standstill before
the end of the physical travel range.
Note
The block only checks the parameterization at the 1st call. This results in a sub-
sequent increased block performance.
As a consequence, reparameterization is not permitted when safety operation is
deactivated. The safety program must be regenerated and loaded each time that
any of the block operating parameters are changed.
3.7.3.2

Ramp monitoring

3. Brake ramp monitoring is activated with a rising edge at EXECUTE.
4. If SAFE_V exceeds the internally calculated maximum permissible value, then output
SBR_OK changes to 0, ERROR changes to 1 and DIAG bit 0 is set.
5. SBR_OK is also set to 0, if in each cycle SAFE_POS changes by more than the maximum po-
sition increase per cycle calculated by the block. This means that the ramp monitoring function
has a two-channel structure.
6. In this case, ERROR also changes to 1 and DIAG bit 0 is set.
7. Monitoring is exited as soon as EXECUTE is returned to 0, and the internally calculated ve-
locity ramp has reached a value of 0.
8. A tolerance value for the velocity and position monitoring can be parameterized using inputs
MAXTOL_V and MAXTOL_POS. SBR_OK is set to 0 if SAFE_V exceeds the internally calcu-
lated ramp + MAXTOL_V, or if the position increase with respect the position at the instant of
the selection is greater than the internally calculated maximum value + MAXTOL_POS.
Warning
STO must be immediately initiated for a 0 signal at SBR_OK.
3.7.3.3

Acknowledging faults

9. DIAG and ERROR are reset to 0 with a positive edge at ACK, assuming that no other fault is
active.
The block immediately indicates that it can be acknowledged with a 1 signal at its output
ACK_REQ. ACK_REQ is reset to 0 after a positive edge at ACK.
10. After SBR_OK has changed to a 0 signal, i.e. the braking ramp was therefore not maintained,
the block can only be acknowledged if the actual velocity at SAFE_V falls below the value at
V_STOP_MONITORING. ACK_REQ then changes to a 1 signal.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
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