How can I connect a siemens drive MM420 to ABB AC800PEC controller.
AC 800PEC provides connectivity, someofthem are built-in (Modbus TCP Slave, CanOpen etc.) or add-on functionalities (Profibus DP v1, Modbus RTU etc.)
First of all, be sure about which of these connectivities are supported by MM420.
According to above link Section 3.1 MM420 only supports RS485 Serial as built in. So you can easily connect via Modbus RTU.
Hope this helps.