Siemens SINUMERIK 840D sl Function Manual page 97

05.08
1–encoder system
For a 1–encoder system, the incremental or absolute encoder of the motor is used
for the safety–related actual values of the NC and drive.
The actual values are generated in a safety–related fashion either directly in the
encoder or in the Sensor Module and are provided – with no–reaction – to the NCK
and the drive using safety–related communications via DRIVE–CLiQ.
Special feature regarding linear motors:
For linear motors, the motor encoder (linear scale) is also the measuring system at
the load. IMS and DMS are one measuring system. The connection is made at the
IMS input of the Sensor Module or directly via DRIVE–CLiQ.
Significance of the coarse encoder position:
For a 1–encoder system, for all position monitoring functions, the accuracy of the
redundant actual value must be assumed to apply. This accuracy depends on the
encoder evaluation. For all encoder evaluation functions that can be used with
Safety Integrated (SME, SMC, motor with DRIVE–CLiQ), the coarse encoder
pulses are redundantly counted including the quadrupling (coarse encoder posi-
tion). The machine manufacturer must select the appropriate encoder with the nec-
essary encoder pulse number for his particular requirements. To do this, the en-
coder resolution must be converted to the accuracy on the load side. This
conversion is dependent on the type of encoder mounting and the type of axis.
Further, gearbox factors, the spindle pitch for linear axes and the radius of the
rotary table for rotary axes must also be taken into account.
Sensor Module cabinet mounted (not used
for encoders with DRIVE–CLiQ interface)
Fig. 5-1 1–encoder system for a feed drive (FD)
© Siemens AG 2008 All Rights Reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
Basics on the Safety Functions Integrated in the System/Drive
DRIVE–CLiQ
Encoder
Gear
Motor
(FD)
5.4 Actual value conditioning
Machine table
Back–
lash
5-97