16 ETHERNET INSTRUCTIONS
16.5 Executing the Protocols Registered for the Predefined Protocol Support Function
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■Canceling protocol execution
A protocol can be canceled during its execution. The canceled protocol stops the processing and completes with an error. If
multiple protocols are being executed sequentially, the current protocol is forcibly terminated, and the subsequent protocols
are not executed.
Note that if the Ethernet-equipped module has started sending data, the send processing cannot be canceled even the
protocol execution is canceled. The following table summarizes the cancellation timings and operation results.
To request a protocol cancellation, use the module label, "Protocol cancellation specification". Set 1 (Cancellation request) to
the module label, "Protocol cancellation specification", of the cancellation-target connection. The label states transition as
follows:
• If a cancellation is requested while no protocol is being executed, the module performs no processing.
• The module periodically checks for a cancellation request. It may take time until the protocol is actually
canceled after the cancellation was requested.
• While the protocol cancellation specification state is "Cancellation requested", another GP.ECPRTCL
instruction cannot be executed.
Protocol operation Cancellation timing (protocol
execution status)
Operation result
Completion status Handling of data
Sending data 'Protocol execution start' to 'Before
transmission start (waiting for
transmission)'
Completed with an error (protocol
cancellation request error)
Data not being sent
'Transmission start' to 'Before
protocol execution completion'
Data being sent
Receiving data Any time Data not being received
Protocol cancellation
specification
Description
No cancellation specified A state that a cancellation has never been requested since the the system was powered on or the CPU module was reset.
Once a protocol cancellation is requested, the label never returns to this state.
Cancellation requested A state that a protocol cancellation has been requested by a user.
The label is in this state until the processing completes.
Cancellation completed A state that the cancellation processing has been completed
Cancellation not specified Cancellation requested Cancellation completed
Set by a user.
Set by a user.
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