Siemens SINUMERIK 840D Description Of Functions page 108

3 Safety-Related Functions
3.5 Safely-reduced speed (SG)
Spindle
Gearbox
1PHxx...
O1 O2
I1 I2
Fig. 3-18 Spindle with 1-encoder system
3-108
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
NCK
I7O
HW
images
I/O
I
...
...
...
O
...
...
...
I
...
...
...
O
...
...
...
PLC
I/O
HW
images
I/O
Note
The above circuit (Fig. 3-16) triggers the request signals E1/E2 for gear stage
switchover for the NCK/PLC and drive simultaneously. There is usually a
delay in the internal gear stage selection because of the different processing
speeds of the two channels (due to the PLC cycle time, the NCK usually
detects the signal change earlier than the PLC). As this cannot be avoided,
gear stage changeover without errors is only possible under the following
conditions:
1. The gear stage is selected at zero speed, the time delay does not cause
an offset of the two SI values.
The gear stage is selected when the motor is moving (e.g. oscillating), i.e. the
time delay also cause an offset of the SI values. In this case, the following
measures are possible:
MD 36942 / or MD 1342 SAFE_POS_TOL must be parameterized as
necessary and resynchronization of the spindle (<axis DB>.DBX 16.6: active
measuring system) must be triggered after gear changeover (if this has not
already been done) to re-align the SI actual values.
Pro-
SGE
cessing
SGA monitoring channel
Bit 0
Bit 1
SBH/SG
Bit 2
SE
SN
Monitoring
comparators
per axis/spindle
NC
Result and data
H function
cross-check
Bit 0
Bit 1
SBH/SG
Bit 2
SE
SN
Monitoring
PLC
comparators
user
program
per axis/spindle
SGE
SGA
monitoring channel
© Siemens AG 2003 All Rights Reserved
11.03
NCK
Drive
SG_02.DSF