The following SIPLUS S7-400 F digital modules are available for use in extreme environmental conditions:

• SIPLUS S7-400 SM 421;
  digital inputs
• SIPLUS S7-400 SM 422;
  digital outputs

SIPLUS S7-400 digital modules are designed for use in the following environmental conditions:

• Extended ambient temperature range from -25 °C to +60 °C
• Where increased resistance to chemical, mechanical and biological loading as well as salt spray is required
• Higher installation altitudes
• In relative humidity up to 100%