Fig. 89 Selection Of The Diagnostic Information Of An Ethercat Slave - Beckhoff EL3773 Documentation

Diagnosis in real time: WorkingCounter, EtherCAT State and Status
Generally speaking an EtherCAT Slave provides a variety of diagnostic information that can be used by the
controlling task.
This diagnostic information relates to differing levels of communication. It therefore has a variety of sources,
and is also updated at various times.
Any application that relies on I/O data from a fieldbus being correct and up to date must make diagnostic
access to the corresponding underlying layers. EtherCAT and the TwinCAT System Manager offer
comprehensive diagnostic elements of this kind. Those diagnostic elements that are helpful to the controlling
task for diagnosis that is accurate for the current cycle when in operation (not during commissioning) are
discussed below.
Fig. 89: Selection of the diagnostic information of an EtherCAT Slave
In general, an EtherCAT Slave offers
• communication diagnosis typical for a slave (diagnosis of successful participation in the exchange of
process data, and correct operating mode)
This diagnosis is the same for all slaves.
as well as
• function diagnosis typical for a channel (device-dependent)
See the corresponding device documentation
The colors in Fig. "Selection of the diagnostic information of an EtherCAT Slave" also correspond to the
variable colors in the System Manager, see Fig. "Basic EtherCAT Slave Diagnosis in the PLC".
Colour Meaning
yellow Input variables from the Slave to the EtherCAT Master, updated in every cycle
red Output variables from the Slave to the EtherCAT Master, updated in every cycle
green Information variables for the EtherCAT Master that are updated acyclically. This means that
it is possible that in any particular cycle they do not represent the latest possible status. It is
therefore useful to read such variables through ADS.
Fig. "Basic EtherCAT Slave Diagnosis in the PLC" shows an example of an implementation of basic
EtherCAT Slave Diagnosis. A Beckhoff EL3102 (2-channel analogue input terminal) is used here, as it offers
both the communication diagnosis typical of a slave and the functional diagnosis that is specific to a channel.
Structures are created as input variables in the PLC, each corresponding to the process image.
EL3773 Version: 2.5
Commissioning
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