The holding brake is not applied when activating the Safe Torque Off function (STO) from the outside via the digital input terminals while executing the "Shutdown" function via the CiA402 control word.
Background:
The functionality for the drive behaviour in the case of an error response has been extended for the firmware versions listed under "Which products are affected?".
In the case of an error, controller inhibit has so far always been set immediately and the inverter has thus always been directly inhibited.
With the new setting option 0x605B=[1] "Deceleration along quick-stop ramp", the drive can be actively stopped by means of a quick stop (QSP) before inhibiting the inverter in the case of a shutdown. In the event of a shutdown, the quick-stop function will be started immediately and this state will remain active until the system has come to a standstill.
If the STO function is triggered from the outside in this state, the inverter will be inhibited immediately but the controller will remain in the quick-stop state and wait until the system has come to a standstill. A connected holding brake will not apply before the system has come to a standstill. Only when the system has come to a standstill, e.g. after reaching the mechanical limitation, the holding brake will be activated.
When does this behaviour occur?
The behaviour occurs when selecting the setting 0x605B=[1] "Deceleration along quick-stop ramp" AND
triggering the STO function after a shutdown command via the CiA control word 0x6040 while the quick stop ramp is still being processed.
Which products are affected?
Servo inverter i950
Short-term measures:
Do not use the new functionality (0x605B=[1]).
Select the parameter setting 0x605B=[0] "Controller inhibit" (default setting).
Evaluation/recommendations:
For safety reasons, applications with active loads, e.g. hoists usually require a second independent system to ensure a safe shutdown of the machine, if an error might lead to major damage.
