Siemens SIMATIC ET 200AL, System Manual

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Time-based IO basics
2.6 Technical implementation
High-precision input/output with Time-based IO
Function Manual, 11/2019, A5E33454822-AC
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OIP model (application cycle factor >= 1)
The user program is started after the delay time. In PIP_Mode 0, the TIO_SYNC instruction
updates the process image. In the other modes, you start by updating the corresponding
process image partition of the outputs in the user program by calling the SYNC_PO system
instruction. As a result, the output data that was calculated in the previous network cycle will
become active during the next network cycle (T
O
). Next the corresponding process image
partition of the inputs is updated in the CPU by SYNC_PI. Processing starts after the data is
transmitted (for example, calculation of the time stamps).
Properties of the OIP model:
● The response time is longer than with the IPO model.
● It is one application cycle longer than permitted by the send clock.
This gives the application more time than with the IPO model.
Influence of accuracy
To estimate the accuracy you need the accuracy of
● TIO module
● Sensor/ actuator
Consult the data sheets of the respective module regarding the accuracy value.
You have to add the individual jitters of the TIO modules and the sensors/actuators. You can
neglect any other influencing factors.
See also
Programming of Time-based IO (Page 28)