Siemens SIMATIC S7-400 Equipment Manual page 25

If some other method of synchronization is used, the pause in sending can be deactivated by
means of the parameter assignment interface.
Note
When XON/XOFF flow control is configured, the user data must not contain the configured XON
or XOFF characters. The default settings are DC1 = 11H for XON and DC3 = 13H for XOFF.
Send Operation
The figure below illustrates a send operation.
Figure 2-4
Point-to-point connection CP 440 Installation and Parameter Assignment
Equipment Manual, 03/2022, A5E00057742-AE
Waiting for
send job
Send job arrived
Sending user
data
Sequence of a send operation
Basic Principles of Serial Data Transmission
2.4 Data Transmission with the ASCII Driver
The amount of data to
be sent is taken from
the LEN parameter of
the send job.
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