The SM 1231 thermocouple 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.
• Thermocouples:
  Four thermocouples each of types J, K, T, E, R, S and N can be used. They are connected directly to the module without amplifiers.
• Mounting location:
  For maximum possible measurement and repeat accuracy, the thermocouple modules should be mounted in locations with low temperature variations.