Siemens ERTEC 200P-2 Manual page 279

If the condition for storing the current counter values in the event registers Ext_Event_1
and Ext_Event_2 occurs simultaneously with a writing of one of these registers, the writ-
ing is treated preferentially.
The storing of the current counter values in the event register Int_Event is triggered by a
positive edge of the INT_EV input. The register is readable by the software and writable;
the setting of the registers after reset is '0000h'.
By storing the current counter values with the edges of the inputs EXT_EV_1, EXT_EV_2
into the event registers Ext_Event_1 and Ext_Event_2 it is possible to measure time
intervals and periods between the inputs EXT_EV_1, EXT_EV_2. By storing the current
counter value with the rising edge of the INT_EV input into the event register Int_Event it
is possible to measure time intervals and periods between write accesses to the SW
event trigger register.
The loading of the counter can be triggered in four different ways:
Loading of the counter by writing the Init_bit in the mode register
Loading of the counter by writing the load register
Automatic loading of the counter after having reached the value '0' in the reload mode
Loading of the counter by an external load signal ( EXT_GATE_TRIG signal)
The counter counts/loads only if the following count/load conditions are met:
Input CLK_EN=1
Count/load clock of the TIMER module active.
Exception: The loading of the counter with the value from the load register always takes
place when writing the Init_bit in the mode register.
Each TIMER activity which is carried out dependent on the edge of an input signal
(INT_GATE_TRIG or EXT_GATE_TRIG, EXT_EV1, 2, INT_EV) becomes effective with
the third CLK_TIMT signal at the latest.
The active edges of the input signals at which the edge evaluation is carried out have to
have a minimum distance, also see "Timing requirements".
Event register:
Each TIMER module has:
Two HW event registers (Ext_Event_1 and Ext_Event_2) in which the current counter
values are stored with an edge of the inputs Ext_Ev_1, Ext_Ev_2 (edge programma-
ble), and
One SW event register (Int_Event) for storing the current counter values with a positive
edge of the input INT_EV.
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Technical data subject to change
279 ERTEC 200P-2 Manual
Version 1.0