Siemens sinumerik 840D sl Function Manual page 364

Detailed description
2.7 Extended stop and retract (ESR)
Figure 2-13
Communication/ control failure
When the NC sign-of-life monitoring responds, a communication/control failure is detected
on the drive bus and a drive-independent ESR is performed if appropriately configured.
Note
Measuring of the intermediate circuit voltage is activated by default, by changing the preset
value from 600 V to 0 V.
In order to ensure that older hardware versions without intermediate circuit measurement are
set up correctly, the following machine data is set under "Calculate controller data":
MD1161 $MD_FIELDVAL_FIXED_LINK_VOLTAGE = 600 V
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DC link voltage monitoring SIMODRIVE 611D
Special functions: Axis Couplings and ESR (M3)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0