Figure 9-3 Example Of Minimum Signal Duration Of An Input Signal During The Update - Siemens SIMATIC S7-400H System Manual

Link-up and update
9.3 Link-up and update
Minimum duration of input signals during update
Program execution is stopped for a certain time during the update (the sections below describe
this in greater detail). To ensure that the CPU can reliably detect changes to input signals
during the update, the following condition must be satisfied:
Min. signal duration > 2 x the time required for I/O update (DP only)
+ call interval of the priority class
+ program execution time of the priority class
+ time required for the update
+ program execution time of higher-priority classes
Example:
Minimum signal duration of an input signal that is evaluated in a priority class > 15 (for example,
OB 40).
Figure 9-3
98
Example of minimum signal duration of an input signal during the update
System Manual, 09/2007, A5E00267695-03
S7-400H