S7-300 FM 351 two-channel positioning module handles the adjustment

Product No. / Product DescriptionListprice / Your price

FM 351 positioning module

  • Two-channel positioning module for rapid-traverse/creep-speed drives
  • 4 digital outputs per channel for motor control
  • Incremental or synchro-serial position decoding


SIMODRIVE Sensor/Motion Connect 500 feature position-measuring systems and preassembled connecting cables for counting and positioning functions.

ApplicationFM 351 positioning module

The FM 351 two-channel positioning module handles the adjustment of mechanical axes on rapid-traverse and creep-speed drives. The module is used for positioning adjustment axes and setting-up axes, preferably with standard motors, controlled via contactors or frequency converters.

The module is used in:

  • Packaging machines
  • Lifting gear and conveying equipment
  • Woodworking machinery
  • Paper and printing machinery
  • Rubber- and plastics-processing machines
  • Machine tools


A positioning controller with the FM 351 features the following essential components:

  • FM 351:
    • For the positioning of two independent axes
  • S7-300 CPU:
    • For sequence control
    • For starting and stopping positioning actions
  • Programming device:
    • For programming the STEP 7 program
    • For parameterizing the FM 351 with STEP 7 using parameterization screen forms
    • For testing and startup
  • Operator panel (optional):
    • For operator control and monitoring of the machine
    • For error diagnostics

The FM 351 and CPU are linked via technology blocks.

Positioning functionality
  • Setup:
    Move the rapid-traverse or creep-speed axis into position at the touch of a button.
  • Absolute incremental feed mode:
    The axis is moved to an absolute target position. The numerical values are stored in a table on the FM 351.
  • Relative incremental feed mode:
    The axis is moved through a set route.
  • Reference point motion:
    For synchronization after the PLC has been turned in when using incremental position encoders.
Special functions
  • Zero offset
  • Set reference point
  • Delete distance to go
Mode of operation

Preparatory steps for a positioning task:

  • Coordination of mechanical system and electronics:
    Easily achieved by entering machine data.
  • Specification of target position and traversing speed via the S7 CPU or the configuring software
  • Transfer of the interface signals from the CPU to the FM 351 (start, stop)

The FM 351 handles the actual positioning task:

  • 4 digital outputs controlling the rapid-traverse, creep-speed, counterclockwise and clockwise functions are assigned to each channel.
  • Creep speed or rapid-traverse/creep speed is specified depending on the distance to the target.
  • After the cutoff point is reached, the module monitors the target approach. After the target area is reached, a signal is sent to the CPU.