Siemens SINUMERIK 840D sl Function Manual page 558

Commissioning
10.7 Replacing a motor or encoder
When service is required (motor defective or encoder defective), it might be necessary to
completely replace the motor or just the motor encoder.
In this case, the motor encoder must be re-calibrated. This influences the behavior of Safety
Integrated if the functionality "safe limit positions" or "Safe Cams" have been activated for the
axis in question, i.e. the axis has the status "safely referenced". Depending on which motor
measuring system is used, it might be necessary to select a different procedure.
The procedure for replacing a motor with absolute value encoder and to replace a motor with
incremental encoder are described in the following text. The end of the Chapter discusses 2-
encoder systems and encoder modules.
Supplementary conditions
As mentioned above, the functionality "safe limit positions" or "Safe Cams" is active for the
axis in question.
The user agreement is set for the axis. This means that the axis has had the status "safely
referenced" at least once - the actual position value of the NC and the SI actual values (axis/
drive) have been appropriately calibrated/aligned.
"Safe limit positions" or "Safe Cams" have been able to be used. A motor or motor encoder
has to be replaced under these general conditions.
Replacing a motor with absolute value encoder
In order to setup the encoder, the offset between the machine zero and the zero of the absolute
encoder was determined.
The calibrated/aligned state is identified using MD34210 $MA_ENC_REFP_STATE = 2.
The important factor when replacing a motor (also without Safety Integrated) is that a defined
position reference can be established with respect to the mechanical parts of the machine. For
example, by mounting and removing the motor at a defined mechanical position or
appropriately re-calibrating the system after the motor has been replaced.
After the old motor has been removed and the new motor installed, another actual position
value is read by the new absolute value encoder (there is no longer a defined reference to the
correctly calibrated actual position value).
Therefore, the following error profile appears when the control boots:
Alarm 27001 Axis <Axis name> error in a monitoring channel, code 1003, values: NCK x, drive
y.
The comparison between the saved stop position and the actual position indicates a larger
deviation than specified in MD36944 $MA_SAFE_REFP_POS_TOL or parameter p9544 "SI
Motion actual value comparison tolerance (referencing)"
The alarm results in a STOP B followed by a STOP A (safe pulse cancellation) for the axis
involved.
Further, the user agreement is withdrawn. This means that the axis loses the status "safely
referenced" in connection with the Alarms 27000/C01797 axis <name of the axis> not safely
referenced.
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Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated