The SM 1231 RTD modules exhibit the same structural features as the other modules of the S7-1200 series:

• Mounting on a DIN rail:
  The modules are snapped onto the rail just to the right of the CPU and connected to one another and with the CPU 12xx by means of the integral backplane bus.
• Direct mounting:
  Drilled holes permit the module to be bolted directly to walls. This type of mounting is recommended for applications subject to strong vibrations.
• Resistance temperature detectors:
  The most popular resistance temperature detectors can be used: Pt 100, Pt 200, Pt 500, Pt 1000, Pt 10000, Ni 100, Ni 120, Ni 1000, Cu 10, FS 150, FS 30, FS 600. They are connected directly to the module without amplifiers and all RTDs must be of the same type. The detectors can be connected with 2, 3 or 4 cables.
• Mounting location:
  For maximum possible measurement and repeat accuracy, the RTD module should be mounted in locations with low temperature variations.
• DIP switches:
  Required settings, e.g. selection of the connected RTDs, should be made using the DIP switches on the module.