Siemens SIMATIC S7-1500 Function Manual page 46

Signal sequence in the IPO model
The following figure shows the signal sequence in the IPO model from the acquisition and
the processing in the CPU to the output of the process values:
①
②
③
④
⑤
Figure 6-1
At time T
data in the IPO model is completed within one data cycle T_DC. The output data is always
available on the I/O in the next data cycle T_DC at time T
With the IPO model, there is a constant execution time from the "input terminal" to the
"output terminal" of T
T + 2×T_DC + T
I
events.
Isochronous mode
Function Manual, 10/2018, A5E43884988-AA
Execution of isochronous mode interrupt OB
"SYNC_PI" instruction
"SYNC_PO" instruction
Isochronous read-in of process values on I/O module at time T
Isochronous output of process values on I/O module at time T
Signal sequence in the IPO model
the process values are read in isochronously on the I/O. The processing of the
I
+ T_DC + T
I
can be guaranteed for the process response time for asynchronous
O
6.1 Program execution according to the IPO model
.
O
Programming isochronous mode
I
O
.
O
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