Main Range of product Modicon M171/M172 Product or component type Programmable controllers Product specific application HVAC and pumping solution Variant Programmable Total inputs/outputs 28 Discrete input number 8 Discrete output number 1 relay outputs SPDT with independent common 3 relay outputs SPST with same common 2 relay outputs SPST with same common 2 relay outputs SPST with independent common Discrete output current 1 A relay SPDT 3 A relay SPST Analogue input number 8 configurable by pair Analogue output number 2 voltage 0...10 V 2 voltage/current 4...20 mA or 0...10 V or PWM (2 kHz) Complementary Number of port 1 CAN port - screw terminal block 1 USB type A - USB type A female 1 USB type mini B - USB device port Mini-B 2 RS485 - screw terminal block Modbus serial link or BACnet MS/TP) 1 Ethernet - RJ45 Modbus TCP and BACnet IP with webserver) Input/Output number 8 digital input 8 analog input 4 analog output 8 digital output Discrete input logic Sink or source (positive/negative) Discrete input voltage 24 V AC/DC