Brake control without DC-bus voltage

Which products are affected?
9400 Single Drive devices (all hardware versions) with integrated brake modules and separate 24 V supply of the control card.

What happens?
The brake cannot be released.

When does the problem occur?
If the DC-bus voltage is switched off and you try to release the brake manually using the LS_Brake POU.
Reason: There is a double basic insulation between the control card and the brake terminals. In order to implement this, the power PCB was equipped with an optocoupler route whose switched-mode power supply is supplied by the DC-bus voltage.

Possible diagnostics?
Brake cannot be released. LU.

Short-term measures/recommendations?
• Switch on the DC-bus voltage.
• The brake connection provides a change-over for direct control using 24 V (9400 Single Drive with integrated brake module, brake release without mains supply).

Evaluation
Non-critical, since the brake remains engaged.