BECKHOFF DK9222-0211-0021 - Manual (Page 5)

I/O
XFC
Application Note DK9222-0211-0021
Time stamp terminals from Beckhoff
EL1252 | 2-channel digital input terminal with time stamp
EL2212 | 2-channel digital output terminal 24 V DC with overexcitation
EL2252 | 2-channel digital output terminal with time stamp, tri-state
In addition to the EtherCAT Terminals, Beckhoff also offers all required components for a control solution that enables very fast
and extremely deterministic reactions. XFC includes all hardware and software components involved in control applications:
optimized input and output components that can pick up signals with high accuracy or initiate tasks, EtherCAT as the very
fast communication network, high-performance Industrial PCs and TwinCAT, the automation software that links all system
components.
Practical example | simultaneity
Without the use of a time stamp, it is not possible from the point of view of the CPU to distinguish changes of a signal within a
fieldbus cycle or to classify them with a temporal accuracy greater than the time pattern dictated by the fieldbus. Therefore, the
simultaneity of events cannot be adequately judged. Thus in fault finding, for example, the time stamps from the various field
devices can be compared with one another in order to differentiate the causes of consequential errors.
Practical example | reference signals in test setups and test benches
External high precision clocks, for example the atomic clock of the Physikalisch-Technische Bundesanstalt (Federal Institute
of Physics and Metrology) in Braunschweig (Brunswick), Germany, are often used to provide the test setup of a device with a
reliable and constant timebase that is valid as a reference measured variable in different series of tests. For simple integration
via decentralized I/Os, the time signal is laid as a clock on a digital input terminal with time stamp, e.g. the EL1252 EtherCAT
Terminal. Since the EtherCAT Terminals work with the high bandwidth of 100 Mbit/s right into the terminals, the controller of
the test setup can fall back on the fed-in time signal and place all events within the system in exact relationship to one another
by the Distributed Clocks function. The deterministics arising from this are identical for all measurement series and allow
concrete conclusions to be drawn between two different series of measurements.
New Automation Technology Beckhoff 5
For application notes see disclaimer on the last page