Communication
11.2 PROFINET
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
841
The TSEND_C instruction is executed asynchronously and implements the following
functions in sequence:
1. Setting up and establishing a communications connection:
TSEND_C sets up a communication connection and establishes this connection if a rising
edge is detected at the REQ parameter and no communication connection is in place yet.
Once the connection has been set up and established, it is automatically maintained and
monitored by the CPU. The connection description specified at the CONNECT parameter
is used to set up the communications connection. The following connection types can be
used:
– TCON_Param structure for the TCP, ISO-on-TCP, and UDP protocols
– WIth V4.1, TCP/UDP: Connection description using the structure TCON_IP_v4 at the
parameter CONNECT
– WIth V4.1, ISO-on-TCP: Connection description using the structure TCON_IP_RFC at
the parameter CONNECT
An existing connection is terminated and the connection which has been set up is
removed when the CPU goes into STOP mode. To set up and establish the connection
again, you must execute TSEND_C again. For information on the number of possible
communication connections, please refer to the technical specifications for your CPU.
2. Sending data via an existing communications connection:
The send job is executed when a rising edge is detected at the REQ parameter. As
described above, the communications connection is established first. You specify the
send area with the DATA parameter. This includes the address and the length of the data
to be sent. Do not use a data area with the data type BOOL or Array of BOOL at the
DATA parameter. With the LEN parameter, you specify the maximum number of bytes
sent with a send job. If using a symbolic name at the DATA parameter, the LEN
parameter should have the value "0".
The data to be sent must not be edited until the send job is completed.
3. Terminating the communications connection:
The communications connection is terminated after the data has been sent if the CONT
parameter had the value "0" at the time of the rising edge at the REQ parameter.
Otherwise, the communications connection will be maintained.
If the send job executes successfully, the DONE parameter is set to "1". The
communications connection may be terminated before this (see the above description of the
dependency on the CONT parameter). Signal state "1" at the DONE parameter is not
confirmation that the data sent has already been read by the communications partner.
TSEND_C is reset when the COM_RST parameter is set to "1". Data loss may occur if data
is being transferred at this point.
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