The FM 451 is a positioning module for adjusting and positioning mechanical drives on the basis of the rapid traverse/creep speed principle.
The FM 451 is used in the SIMATIC S7-400. The module makes it possible to position three axes independently of one another. The axes in question may be linear axes with limited traversing range or continuously rotating rotary axes.
Incremental encoders and SSI encoders can be used for position decoding.