Siemens simatic s7-400 FM 450-1, User Manual, Page: 88 / 130

Modes, settings, parameters and commands
8.12 Initiating a process interrupt
Counter module FM 450-1
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Manual, 02/2014, A5E03648739-02
Parameter assignment Behavior of the FM 450-1 counter
Parameter assignment
"single setting of counter"
The counter is set only at the first rising edge of the zero mark.
If the counter is to be set again, you must first set ENSET_UP or
ENSET_DN again (edge evaluation). The counter is then set again with
the next rising edge of the zero mark.
Parameter assignment
"multiple setting of
counter"
As long as ENSET_UP and/or ENSET_DN are set, the counter will be set
with each rising edge of the zero mark.
Note
It is imperative that you set one of the two variables, ENSET_UP or/and ENSET_DN and
input 1I2 (2I2) so that the relevant counter can be set with the zero mark.
Single setting with the zero mark
The following figure shows counter 1 being set once with the zero mark. In the case
represented here, only ENSET_UP is set, i.e., the counter is set during up counting.
The relevant counter is set with the first rising edge of the zero mark as long as ENSET_UP
and input 1I2 are set.
If you want to set counter°1 again, you must reset ENSET_UP and then set it again. If input
1I2 is not set, setting is performed with the first zero mark after setting 1/2. If input 1I2 is set,
setting takes place with the next zero mark.
The situation is analogous for counter 2 with input 2I2.
Figure 8-9 Single setting of counter 1 with the zero mark