Values Of The Interval Counter; Address; Interval Counter (Modaddr + 12); Interval Counter (Modaddr + 13...15) - Siemens SIMATIC S7-300 Manual

4.5

Values of the interval counter

Address

The pulse input values determined by SM 335 or saved to memory starting at the I/O
address ModAddr + 12.
Table 4- 2
MOD address
+12
+13
+14
+15

Interval counter (ModAddr + 12)

The interval counter is a continuous counter with a range from 0 to 255. The counter is
initialized internally after the first pulse is detected. The interval counter is incremented by
the count of "1" at the second pulse input. The interval counter is incremented by the count
of "1" at every further pulse input.
SM 335 saves the currently detected intervals to the data byte at the address "ModAddr +
12". The value is '0' as long as no interval was detected. The interval counter is incremented
by the count of "1" at each detected pulse.

Interval counter (ModAddr + 13...15)

Within the duration of an interval, SM 335 counts the time up to the end of the interval in time
slices of 0.5 μs. SM 335 saves the value for the interval duration to 3 bytes starting at
ModAddr + 13. The value of "Module start address + 13" is greater than the value of "Module
start address + 14" byte. "Module start address + 15" byte has the lowest value.
Overflow
SM 335 interprets an interval with a duration greater than 16777215 (FF FF FF
μs (8.3886075 s) as overflow and no longer as interval. The value for the interval duration
freezes at "FF FF FF
interval starts at the next pulse input. The internal duration is measured once again. The
interval counter is incremented again by the count of "1" if a valid interval is measured at the
next pulse input.
SM 335 - High-speed analog mixed module for SIMATIC S7-300
Manual, 02/2009, A5E02409063-01
Values of the pulse input
Content
Interval counter
Interval duration byte 1
Interval duration byte 2
Interval duration byte 3
" and the interval counter is incremented by the count of "1". A new
H
Interval counter input
4.5 Values of the interval counter
) times 0.5
H
75