Analog Values; Number Of End Of Cycle Interrupts (Modaddr + 8) - Siemens SIMATIC S7-300 Manual

Data exchange with SM 335
3.1 Access via I/O addresses
Analog values (ModAddr + 0...7)
For information about the binary notation of analog values in the CPU and the specific
notation associated with a specific analog value, refer to chapters Representation of analog
values of analog input channels (Page 40) and Representation of analog values for analog
output channels (Page 42).

Number of end of cycle interrupts (ModAddr + 8)

The end of cycle interrupt can be used to synchronize a user program by calling OB 40. This
interrupt also facilitates fast execution of the user program (e.g., for control loop routines).
However, certain scenarios can prevent SM 335 from outputting the interrupt:
● after generation of a large number of simultaneous hardware interrupts
● in the special "Comparator" mode
SM 335 suppresses end of cycle interrupts as long as the special "Comparator" mode is
activated.
SM 335 saves the number of the end of cycle interrupts (1 + the number of failed end of
cycle interrupts) to byte ModAddr + 8 after the "Comparator" mode has been terminated.
Example: Content of byte 8 = 5, i.e. only one OB 40 call is generated for the duration of 5
end of cycle interrupts.
The value is also available in the local data of OB 40; refer to chapter Hardware interrupt
(Page 60). You should preferably run the evaluation by calling OB 40 in order to ensure
consistency of the measured value and of the number of end of cycle interrupts.
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SM 335 - High-speed analog mixed module for SIMATIC S7-300
Manual, 02/2009, A5E02409063-01