Siemens SINUMERIK 840D sl Function Manual page 140

Safety Functions Integrated in the System/Drive
6.3 Safe Stops A–F
Warning
!
If an internal or external fault occurs, none or only some of the parameterized
safety functions are available during the STOP F response triggered by the fault.
This must be carefully taken into account when parameterizing the delay time
between STOP F and STOP B (MD 36955/p9555) and must be taken into account
in the risk analysis performed by the machine manufacturer. This is especially true
for vertical axes.
Note
A delay time between STOP F and STOP B should only be set, if, during this time,
an alternative response is initiated by evaluating the system variables
$VA_XFAULTSI and $A_XFAULTSI.
Further, when using the delay time, a monitoring function should always be active
– also in the automatic mode (e.g. SE, SN, SG with high limit switch). For
example, if the SBH monitoring function is only active on the drive side, for
example because of the (single–channel) failure of a door switch, then although
this results in a STOP F, the STOP F –> STOP B delay time on the NCK side is
not started if previously no monitoring function was active. This means that in this
case, the drive responds with a STOP B (however this is also initiated in the NCK
due to the exchange of the stop responses), but this is not displayed in the NCK
variables $VA_XFAULTSI and $A_XFAULTSI.
The appropriate monitoring functions of the drive (e.g. when SBH is selected) are
also executed instantaneously without any delay.
Example 1 – delaying the transition from STOP F to STOP B:
The speed characteristics of an axis for parameterized stopping are shown in Fig.
6-7. In this case, the axis should continue 500 ms and then brake along the para-
meterized ramp. A delay time of 2.5 s is selected until STOP B is initiated
($MA_SAFE_STOP_SWITCH_TIME_F).
v
Fig. 6-7
6-140
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
Continue to traverse (ESR)
t2
t1
Velocity characteristic of an SI axis when stopping with STOP F
Braking along a ramp =
stopping (ESR)
t3
© Siemens AG 2008 All Rights Reserved
05.08
t