An economical solution, these PLCs focus on control of HVAC, refrigeration and pumping systems with flexible scheduling, occupancy sensing and analog controls. The software is EcoStruxure™ machine expert - HVAC, a powerful configuration software compliant with IEC 61131-3. (Not included with or related to EcoStruxure™ machine expert or EcoStruxure™ machine expert - basic.) M171 and M172 controllers can handle small to very large machines and can be networked to handle large systems.