Several issues could be the cause of this. A few typical causes are listed below: 

- Communication cable is unplugged/damaged.

- Drive is in a boot up state. 

- Flash card is unplugged. 

- Installed hardware revisions are not correct. 

PG/PC 

- Programming device has not been assigned in NetPro.

- Correct communication path, Device/S7ONLINE, has not been selected. 

- Incorrect communication protocol has been set. 

Profinet 

- IP address on the programming device is not set to the range of the drive or is the same address. 

- Using an eWON connection. Profibus 

- Baud rate is set incorrectly. 

- Node address on the programming device is the same as the drive. 

- “PG/PC is the only master on the bus” is/is not set. This is specific for direct connection to a drive or via a routing method.