23 January 2021
What can cause an SLF fault on the ATV312 drive?
Altivar ATV31 and ATV312
Serial link fault or missing HMI with drive programmed for HMI or LCC control set to yes.
Make sure parameter LCC in the CTL menu is set to no if you are not using a remote HMI.
Also verify that neither Fr1 or Cd1 are set to LCC.
NOTE: LCC parameter and the choice of LCC under Fr1 and Cd1 will only be available if a remote keypad is connected to the drive or when programming via SoMove.
If the remote keypad is missing or disconnected, you will get the SLF fault and the video below reviews how to clear it.
Review this process in the provided video below:
SLF can also occur when using ModBus to set the drive's speed (Fr1 or Fr2 set to MdB) or to start/stop the drive (Cd1 or Cd2 set to MdB) if the drive doesn't see a valid read or write request within the programmed communication time out period.
Parameter tto [Modbus time out] in the Communication menu is adjustable between 0.1 and 30 seconds. The Factory default setting is 10.0 seconds). If Modbus is being used for speed reference or control, the drive must see a read or write request within that time out period or the drive will fault on SLF.
To resolve: read/write more frequently, verify Modbus wiring, routing and connections, or increase the timeout period.