Siemens SINUMERIK 840D Description Of Functions page 469

11.03
8.7 Replacing a motor or encoder
References for References:
SINUMERIK 840D
Description
The following information essentially refers to replacing a motor encoder. The
limitations that apply as well as the procedures are essentially the same when
replacing a direct measuring system.
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 affects the behavior
of Safety Integrated if the functionality "Safe limit positions" or "Safe cams" has
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 procedures 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.
Limitations 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, i.e. the axis has had the status "safely
referenced" at least once – adjustment between the actual position value of the
NC and the SI actual values (axis/drive) has been carried-out.
"Safe limit positions" or "Safe cams" have been able to be used.
A motor or motor encoder must replaced under these limitations/conditions.
Replacing a motor with In order to set the encoder, the offset between the machine zero and the zero
absolute value of the absolute encoder was determined and saved in the SRAM of the
encoder NC module.
The calibrated state is identified by the control using MD 34210:
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 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 runs-up:
Alarm 27001
Code 1003, values: NCK 0, drive 0
The comparison between the saved standstill position and the actual position
indicates a larger deviation than that specified in MD 36944:
$MA_SAFE_REFP_POS_TOL (actual value comparison tolerance
(referencing)) or
MD 1344: $MD_SAFE_REFP_POS_TOL
© Siemens AG 2003 All Rights Reserved
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
/IAD/, Installation and Start-up Guide
/R1/, Reference Point Approach
Axis <name of the axis> fault in a monitoring channel,
8 Application examples
8.7 Replacing a motor or encoder
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