Issue:
Is it possible to reset the STO state and SAFF error via Modbus communication on Altivar 320.

Product Line:
Altivar 320

Environment:
All

Cause:
Network reset

Resolution:
STO displayed on HMI is not an error. It is normal state when motor is in safe stop. As soon as remove STO (by deactivating safety signal), the drive can be started again including starting over modbus. STO cannot be removed by communication, it is against the safety requirements. Because STO can be triggered by STO input or by other logic inputs (for example LI3+LI4 if these inputs are configured in Altivar 320 safety configuration), the same principle is used for removing STO. Dedicated inputs (e.g. STO, LI3+LI4) must return back to deactivate STO conditions. To start the motor, new run command must be applied.

If there is a safety error (SAFF) then it is necessary to restart the drive. This type of error signalize that there is something wrong with safety and deeper analyze is recommended. The easiest reset is to power cycle the drive. However, there is one register, (address 7128) that can execute product restart. By writing value 1 into address 7128, the drive is restarted, exactly like new power up.
Remember to write value 1 into 7128 only once. After that write either value 0 or do not write anything.

Released for: Schneider Electric Saudi Arabia