ctrlX SAFETY "SafeMotion"
In step 2, monitoring via two channels takes place to find out whether
the actual velocity is within the velocity envelope curve (P-0-3238). The
velocity envelope curve is generated by the drive by means of the deceler-
ation ramp (P‑0‑3263.0.5, SMO: SMD-E deceleration) and the jerk limit
(P‑0‑3263.0.8, SMO: SMD-E jerk). The drive calculates the start value of
the velocity envelope curve from the current actual velocity plus a toler-
ance (P-0-3263.0.4).
If a jerk > "0" has been set in "P-0-3263.0.8, SMO: SMD-E jerk, the decel-
eration ramp for limiting the jerk is filtered via a PT1 element. The time
constant of the filter can be determined as follows:
T
PT1
= P‑0‑3263.0.5 / P‑0‑3263.0.8
NOTE: Via "P‑0‑3263.0.4, SMO: Velocity window SMD-E and
"P‑0‑3263.0.8, SMO: SMD-E jerk", the transient oscillation of the velocity
to the new target velocity is facilitated.
NOTE: If the monitoring limit of the “Safe maximum velocity (SMS)"
(P‑0‑3270.0.2) or an active “Safely limited velocity (SLS)" (P‑0‑3290.x.2)
is below the calculated velocity envelope curve (P‑0‑3238), the envelope
curve acts as monitoring limit. When exceeding the monitoring limit, the
safety function reports an error.
– Section 3: "Monitoring the "velocity window of Safe standstill"" until
switching to "Safe standstill error" takes place:
After the velocity envelope curve (P-0-3238) has reached the velocity
window (P-0-3255, SMO: Velocity threshold for Safe standstill), moni-
toring ensures that the actual velocity is smaller than the velocity window
until switching to "Safe standstill" error takes place.
The parameters involved can be used to adjust the monitoring function to
different applications; primarily, this can be accomplished with P-0-3263.0.3
and P-0-3263.0.5.
NOTE: The transition to "Safe standstill error" is terminated ahead of time,
when the drive has removed drive enable and the actual velocity is smaller
than the parameterized velocity window (P-0-3255).
Compensating transient oscillation processes
In the case of the transition functions "Safely-monitored deceleration" in the
case of error (based on actual velocity) (SMD-E) and Safely-monitored decel-
eration based on actual velocity (SMD
ActVel
), it is possible to configure that
the axis may still move by an incorrect distance after the "velocity envelope
curve" (P-0-3238) has been exceeded, before Safe Motion switches off with the
error F7051 or F8351. This can be used for transient oscillation processes to
standstill or for axis motions after the output stage was switched off.
Monitoring of the incorrect distance becomes active under the following condi-
tions:
●
The configuration specifies that the axis may still move by an incorrect dis-
tance (P-0-3280.0.1, bit 7="1").
●
One of the following transitions is active:
–
Transition to special mode "Safe standstill" (SMES, SMST1, SMST2) with
active deceleration monitoring (SMD
ActVel
)
– Transition to error state with active deceleration monitoring (SMD-E)
● The velocity envelope curve of deceleration monitoring falls below the
velocity window (2 × “P-0-3255, SMO: Velocity threshold for safe standstill")
● The actual velocity is greater than the velocity envelope curve of decelera-
tion monitoring (P-0-3238)
The incorrect distance is determined by adding the actual velocity values.
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