Functions of step relays:
The step relay S can easily set up the procedure in the industrial automation, which is the most basic device in the the
sequential function chart (SFC) and has to be used with STL, RET instructions.
The device No. of S is S0 ~ S1023 (total 1,024 points) and both step relay S and output relay Y have output coils and
contact A, B, and there is no limitation on the times of using the contact.
