Counting and measuring This section contains information on the following topics:Counting and measuring basics (S7-300, S7-400)Using FM 350-1 (S7-300, S7-400)Using FM 350-2 (S7-300, S7-400)Using FM 450-1 (S7-300, S7-400)Using ET 200S 1Count24V (S7-300, S7-400)Using ET 200S 1Count5V (S7-300, S7-400)Using ET 200S 2PULSE (S7-300, S7-400)