A portable screw fastener driving tool is driven electrically from a solid state inverter and intended to be coupled to any selected one in a set of screw fastener engaging members, each demanding a drive enabling tightening of the engaged fastener by parameters (e.g. torque, angle, speed) specific to its size or type. Code elements are provided on the members in a binary code pattern specific for each member. Sensors on the tool read the code pattern on the member connected to the tool and serve it electrically to a decoding unit which transforms the read binary pattern to signals adapted to control the inverter the way the member demands.