Located on the front panel of the module are:

• Switches for input status:
  16 switches are used to simulate input signals.
• LEDs for output status:
  16 LEDs indicate the signal status at the outputs.
• Mode selector:
  The user can set one of the following three modes using a screwdriver:
  • 16 inputs (input simulation only),
  • 16 outputs (output simulation only),
  • 8 inputs (input and output simulation) and
  • 8 outputs (input and output simulation).

These operating elements are protected by the front cover. The module is snapped onto the rail and connected to the S7-300 backplane bus. The power is supplied via the backplane bus.