Hello Rollex;

A gsd file is required only if you are setting the Altivar as a Profibus-DP slave,

For Modbus networks you do not need this type of file, you must define the network parameters using the MB_Comm_Load function (for the S7-1200 PLC), then use the MB_Master function for every read/write operation you want to do over the network.

Of course you must have an idea of the Modbus mapping (register addresses of the Modbus slave) to know what addresses must be used for control of the drive.

See the following FAQ:

How do you establish a MODBUS-RTU communication with S7-1200

Hope this helps,

Daniel Chartier