Function & operation
The FM 451 decodes quadrature encoder signals (A, B) and the DATA/notDATA lines for absolute encoder SSI interfaces, with a zero-mark signal absent on this variant. Each of the three axes handles 4 inputs and 4 outputs, supporting rapid traverse, creep, run right, and run left motion profiles directly from the module without burdening the CPU.
Applications
This positioning module is used in S7-400-based machine tools, packaging lines, and assembly stations where three independent axes must be coordinated for point-to-point moves, tool positioning, or synchronized pick-and-place cycles. The on-board motion functions offload real-time positioning from the CPU, freeing it for higher-level logic and HMI communication.