Siemens SIMATIC ET 200SP Manual page 38

4.2.5 Isochronous mode
The technology module supports the "Isochronous mode" system function. Counter values
can be acquired in a fixed system cycle with this system function.
In isochronous mode, the cycle of the user program, the transmission of the input signals
and processing in the technology module are synchronized. A status change of a digital input
immediately triggers the specified reaction of the technology module and the change of the
status bit of the digital input in the feedback interface.
Use an OB of type "MC-Servo" in this operating mode. Isochronous mode is needed when
using the output cam and cam track technology objects. When the measuring input
technology is used in combination with hardware digital input DI1, isochronous mode is not
needed.
Data processing
The data that was transmitted to the technology module in the current bus cycle via the
control interface takes effect when it is processed in the internal technology module cycle. At
the time the input data is read in (T
made available in the feedback interface for retrieval in the current bus cycle. In contrast to
the other status bits, the STS_DI2 status bit is acquired in isochronous mode asynchronously
to the time T
Isochronous mode parameters
In isochronous mode, the "Filter frequency" parameter can affect the isochronous mode
parameters of the sync domain.
Because the isochronous mode parameters are not checked in RUN, overflows can occur if
you change the parameters in RUN. To prevent overflows, select the option with the largest
time required in the offline parameter assignment.
Additional information
You can find a detailed description of isochronous mode in the following:
● In the isochronous mode function manual as a download from the Internet
(https://support.industry.siemens.com/cs/ww/en/view/109755401).
● Function manual PROFINET with STEP 7 available for download on the Internet
(https://support.industry.siemens.com/cs/ww/en/view/49948856)
TM Count 1x24V (6ES7138‑6AA01‑0BA0) technology module
Manual, 07/2019, A5E33002339-AD
), the counter value and the status bits are acquired and
i
.
i
4.2 Position input for ""Motion Control"" technology object
Configuring/address space
37