Retracting - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
Safety notes and instructions
Block F_SAFE_POS signals a 0 signal at POS_VALID via output ERROR = 1.
When POS_VALID goes to zero, a user interconnection must initiate a stop re-
sponse in the drive. All other blocks flag this state using an error code; to avoid a
lot of messages occurring at any one time, ERROR is not again set to a 1. The
end stops and the envelope curve are no longer monitored. Maximum velocity
V_MAX as well as the validity of the velocity actual value SAFE_V are still moni-
tored. End stop and envelope curve monitoring errors can be immediately
acknowledged, X_NEGATIVE_OK, X_POSITIVE_OK and SLS_OK are again set.
If a 1 signal is again present at POS_VALID, the DIAG bit 5 is reset, and the end
stop and envelope curve monitoring continued.
15. If a 1 signal is again present at POS_VALID, DIAG bit 5 is reset.
16. If a 0 signal is available at V_VALID, then DIAG bit 6 is set, until acknowledgment, ERROR
remains in the actual state, assuming that no additional faults/errors occur as a result of an-
other active monitoring function. All other outputs maintain their actual state until acknowl-
edgment, or the cancellation of RELEASE
Safety notes and instructions
Block F_SAFE_POS signals a 0 signal to V_VALID via output ERROR = 1. When
V_VALID goes to zero, a user interconnection must initiate a stop response in the
drive. All other blocks flag this state using an error code; to avoid a lot of messag-
es occurring at any one time, ERROR is not again set to a 1. The maximum veloc-
ity and the envelope curve are no longer monitored. Active maximum velocity and
envelope curve monitoring errors can be immediately acknowledged, SLS_OK is
again set. Retraction via RELEASE can be exited normally,
MOVE_POSITIVE_OK and MOVE_NEGATIVE_OK are set again. If the axis is not
in a valid position range at this time, X_NEGATIVE_OK or X_POSITIVE_OK is
withdrawn and ERROR set.
If a 1 signal is again present at V_VALID, the DIAG bit 6 is reset, and the maxi-
mum velocity and envelope curve monitoring continued.
17. If a 1 signal is again present at V_VALID, DIAG bit 6 is reset.
18. If the permitted travel range is to be exited, i.e. SAFE_POS values are higher than
X_POSITIVE or less than X_NEGATIVE, then the block behaves in a similar fashion to the
"F_SLP_MONITOR" block (Chapter 3.5).
Depending on the direction in which the travel range was exited, X_POSITIVE_OK or
X_NEGATIVE_OK is set to 0. In the user interconnection, a stop response should be initiated
in the drive.
3.6.3.3

Retracting

19. The block retraction function can be activated by selecting RELEASE. If the system is within
the permitted travel range, MOVE_POSITIVE_OK and MOVE_NEGATIVE_OK are reset to 1,
at SLS_THRESHOLD, the velocity parameterized at VMAX_RELEASE is output, and the sys-
tem internally monitors against this value. The velocity envelope curve is still monitored. If this
supplies a more restrictive value for the permitted velocity than VMAX_RELEASE, then the
permitted velocity is limited to the more restrictive value. If the permitted travel range is exited,
the block responds as described under Point 18.
20. The block retraction function can be activated using a positive edge at RELEASE in order to
travel from the end stop back into the permitted travel range. The velocity parameterized at
VMAX_RELEASE is then output at the SLS_THRESHOLD output, and depending on the di-
rection in which the end range was violated, MOVE_POSITIVE_OK or
MOVE_NEGATIVE_OK is set to 0, in order to prevent additional motion into the end zone.
MOVE_POSITIVE_OK = 0 inhibits motion in the positive direction, MOVE_NEGATIVE_OK = 0
inhibits motion in the negative direction.
Note
The signal for RELEASE must be generated in a safety-related fashion, e.g. by
using a key-operated switch or similar device.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
.
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