Siemens SINUMERIK 840D sl Function Manual page 85

Combining encoder types
Various combinations can be derived from the basic types.
Note: x → encoder connection
* A list of the Siemens encoders and motors permissible for Safety Integrated Functions can be obtained
from your local SIEMENS contact partner.
1-encoder system
For a 1-encoder system, the motor encoder is used for the safety-related actual values of the
NC and drive.
If an encoder fault develops, and a safety-related function is active, then STOP B is initiated,
followed by a STOP A.
It is possible to parameterize the response for an encoder error for 1-encoder safety systems
using encoder parameter p9516 (SI Motion encoder configuration safe functions (CU)).
p9516; bit 4 = 0 immediate STOP A for encoder errors
p9516; bit 4 = 1 → the drive is braked with STOP F → B → A.
The precondition that the axis is braked with a STOP F → B → A, is that the SINAMICS
parameter p9560 and MD36960 are set to "0".
Otherwise the actual value frozen by the encoder error can simulate downtime and therefore
cause a premature switch from STOP B to STOP A.
Braking during an encoder fault takes place via the automatic switchover to encoderless
operation. Requirement here is that encoderless operation is commissioned for the
corresponding drive. The default setting of p9516, bit 4 is "0".
As a result of the encoder fault, and the fact that internally the speed is set to a value of 0 (a
valid actual value is no longer available), i.e. no SBR monitoring is possible while STOP B is
active.
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:
The motor encoder (linear scale) of linear motors also acts as load measuring system. 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:
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Basics regarding the safety functions integrated in the system/drive
Incremental encoder
at the motor at the load
x
---
---
x
x
---
Absolute encoder
at the motor
--- ---
--- x
x x
x ---
--- ---
--- x
6.4 Actual value conditioning
Remarks
at the load
--- 1-encoder system*
--- 1-encoder system*
--- 2-encoder system*
--- 2-encoder system*
x 2-encoder system*
x 2-encoder system*
85