Interval Counter Input
A shielded, twisted-pair cable must be used. Connect the cable shield with the
grounded rack via the shield connection in the same manner as all the other ana-
The switch and the cam must be such that the former remains closed for at least
1 ms and open for at least 1 ms at the highest attainable speed.
The interval counter input is isolated from the other connections, and can thus form
no ground loops with them.
The input is sufficiently grounded when the 24 V load voltage is used to power it
and the frame of the 24 V load voltage source has been grounded (see SIMATIC
S7-300, Hardware and InstallationModule).
SM 335 – High-Speed Analog Input/Output Module for the SIMATIC S7-300