Communications
6.1 PROFINET instructions (T-blocks)
Easy Book
74
Manual, 05/2009, A5E02486774-01
The CPU uses the Transport Connection Protocol (TCP) and the ISO Transport over TCP
(RFC 1006) application protocols. When configuring a connection with a CPU for ISO-over-
TCP, use only ASCII characters in the TSAP extension for the passive communication
partners.
There are two ways to communicate using PROFINET:
●
Direct connection: Use direct communication when you are using a programming device,
HMI, or another CPU connected to a single CPU.
●
Network connection: Use network communications when you are connecting more than
two devices (for example, CPUs, HMI panels, programming devices, and non-Siemens
devices).
An Ethernet switch is not required for a direct connection between a programming device or
HMI and a CPU. An Ethernet switch is required for a network with more than two CPUs or
HMI devices.
Note
The PROFINET port on the CPU does not contain an Ethernet switching device. You can
use a rack-mounted Siemens CSM1277 4-port Ethernet switch to connect your CPUs and
HMI devices.
6.1
PROFINET instructions (T-blocks)
Use the T-block instructions only in a program cycle OB (such as OB 1).
TSEND_C establishes a TCP or ISO on TCP communication
connection to a partner station, sends data, and can terminate
the connection. After the connection is set up and established,
it is automatically maintained and monitored by the CPU.
TSEND_C combines the functions of TCON, TDISCON and
TSEND.
●
To establish a connection, execute TSEND_C with CONT = 1. After successful
establishing of the connection, set the DONE parameter for one cycle.
●
To terminate the communication connection, execute TSEND_C with CONT = 0. The
connection will be aborted immediately. This also affects the receiving station. The
connection will be closed there and data inside the receive buffer could be lost.
●
To send data over an established connection, execute TSEND_C with a rising edge on
REQ. After a successful send operation, TSEND_C sets the DONE parameter for one
cycle.
●
To establish a connection and send data, execute TSEND_C with CONT =1 and REQ =
1. After a successful send operation, TSEND_C sets the DONE parameter for one cycle.