We are 3 guys doing our bacholer in automation, and we are trying to buy a siemens starter kit to use a s7-1200 with hmi and a di add-on(cheapest) to control 16 npn sensor(diffuse photo sensors analog). We are wondering if it is possible to connect the sensors directly to the di add-on. the sensors have an output of 300mA. As i understand we need to connect the sensor to a source of 24v and ground. If we can not connect the sensores directly to the di module what is the cheapest way to transform the output of the sensor? from teh di add-on datasheet ● Type of input voltage DC ● Rated value (DC) 24 V ● for signal “0” 5 V DC at 1 mA ● for signal “1” 15 VDC at 2.5 mA Input current ● for signal “0”, max. (permissible quiescent current) 1 mA ● for signal “1”, min. 2.5 mA ● for signal “1”, typ. 4 mA; Typical