Safety Functions - Siemens SINUMERIK 840D sl Function Manual

03.06
S For a 1-encoder system, encoder faults are detected by various HW and SW
monitoring functions. It is not permissible that these monitoring functions are
de-activated and they must be parameterized carefully. Depending on the fault
type and which monitor responds, a Category 0 or Category 1 stop function ac-
cording to EN 60204–1 (defined as STOP A or B in SINUMERIK Safety Integra-
ted) is activated.
S The Category 0 stop function according to EN 60204–1 (defined as STOP A in
Safety Integrated) means that the spindles/axes are not braked to zero speed,
but coast to a stop (this may take an appropriately long time depending on the
level of kinetic energy involved). This must be included in the protective door
locking mechanism logic (e.g. with the logic operation n<n
S When a limit value is violated, the speed may exceed the set value briefly or the
axis/spindle may overshoot the setpoint position to a greater or lesser degree
during the period between error detection and system response. This depends
on the dynamic response of the drive and the parameters/machine data set-
tings that have been entered (see Chapter 6, "System/drive integrated safety
functions").
S A position-controlled axis may be forced out of the safe operating stop state
(SBH) by mechanical forces that are greater than the max. axis torque. In such
cases, a stop function, Category 1 according to EN 60204–1 (STOP B) is acti-
vated.
S Safety Integrated is not capable of detecting parameterization and programming
errors made by the machine manufacturer. The required level of safety can only
be assured by thorough and careful acceptance testing.
S Motor modules and motors must always be replaced with the same equipment
type. If this is not the case, the parameters will no longer match the actual con-
figuration – causing Safety Integrated to respond incorrectly. The axis involved
must be re-commissioned if an encoder is replaced.
S If, for a 1-encoder system, the encoder signals remain at a steady-state due to
an encoder fault (i.e. they no longer following the motion, but have a correct
signal level), then when the axis is stationary (e.g. in SBH), this fault is not de-
tected. Generally, the axis is kept at a standstill by the active closed-loop con-
trol.
Especially for vertical (suspended) axes, from a closed-loop control-related per-
spective, it is conceivable that such an axis can move downwards without this
being detected. For the above mentioned encoder fault, the risk is only possible
for a few encoder types as a result of their principle of operation (e.g. encoders
with microprocessor-controlled signal generation).
© Siemens AG, 2006. All rights reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
System Features
3.2 Residual risks
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