(From Sw 6.4.15) - Siemens SINUMERIK 840D Description Of Functions

3 Safety-Related Functions
3.13 Behavior of Safety Integrated when the drive bus fails (from SW 6.4.15)
3.13 Behavior of Safety Integrated when the drive bus fails

(from SW 6.4.15)

When the drive bus fails, then communications between the drive and NCK
required for SI also fail. The pulses are immediately cancelled from both
channels. This pulse cancellation must be delayed for a short time so that in
this particular fault situation, a drive-autonomous response (ESR) can be
carried-out at the machine.
References: Programming Guide Workshop Planning (PGA)
This is the reason that after a bus failure has been detected, there must be a
delay before canceling the pulses both in the NCK monitoring channel and in
the drive monitoring channel. The selected axial SI functionality (SG,SE, SBH)
at the instant that the drive bus failed, is still available through one channel in
the drive monitoring channel. The NCK monitoring channel can no longer be
monitored as there is no actual value.
The PLC SPL remains functional in the scope in which the drive monitoring
channel is not required. From the PLC-SPL it is not possible to select another
monitoring functionality or immediately cancel the pulses via an external
Stop A.
The NCK-SPL also remains functional if it does not receive its input quantities
($A_INSE) from the DMP modules connected to the drive bus – but instead via
PROFIsafe I/O or the local inputs on the NCU. If another axial monitoring
function (e.g. SE stage changeover) is selected, this remains ineffective as the
axial NCK monitoring functions are de-activated. However, when an external
STOP A is selected, this results in the pulses being immediately cancelled via
terminal 663 – just the same as for an SBH selection. An SG changeover can
also result in immediate pulse cancellation.
If the NCK-SGA "enable pulses" is not output via the local outputs on the NCU,
but via the DMP modules on the drive bus, then it is not possible to delay the
pulse cancellation via terminal 663. The DMP modules delete their outputs
when a drive bus failure is detected.
If the internal pulse cancellation (also refer to Section 3.1.2 "Shutdown paths")
is used, then the SGA "externally enable pulses" must be connected to terminal
663. It is no longer possible to internally cancel the pulses via the drive bus. In
this case, the SGA "externally enable pulses" must be output via the local
outputs on the NCU.
Activation The delay time up to pulse cancellation via terminal 663 must be parameterized
for a value greater than 0 in the NCK machine data 10089
$MN_SAFE_PULSE_DIS_TIME_BUSFAIL and in the appropriate drive
machine data 1380 MD_SB_PULSE_DISABLE_TIME. For a standard value of
0, the function is de-activated; when the drive bus fails, the pulse enable signal
for terminal 663 is immediately withdrawn.
3.13.1 Behavior of the axial NCK monitoring channel
If a delayed pulse cancellation is parameterized using MD
$MN_SAFE_PULSE_DIS_TIME_BUSFAIL, after a bus failure, the SGA leave
all of the axial SI monitoring channels in their old condition. After this delay time
has expired, all SGA are, as before, deleted. The axial monitoring functions are
immediately no longer processed after the bus fails as the basis for the
monitoring function – the safe actual value – is no longer available.
3-198
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
© Siemens AG 2003 All Rights Reserved
11.03