Siemens SIMATIC S5 Manual page 115

Data Transfer with PLC-to-PLC Connections
6.3 Programming
Connections Using Standard Function Blocks
This section explains the structure of the control programs for two programmable controllers.
Example:
PLC 1 and PLC 2 are to exchange data with one another, i.e., they will transmit and receive. Refer
to section 6.1 for the description of the hardware configuration.
The control program in FB105 for transmitting data is structured as illustrated below.
yes
Call up of function block L2-SEND
Has PAFE message or STBS error occurred?
yes
Transmit request is
Confirm transmit request. (The program resets the transmit trigger bit.)
repeated automati-
cally (call up of L2-
End
SEND)
The control program in FB15 for receiving data is structured as illustrated below.
yes
Call up of function block L2-RECEIVE; data are fetched.
yes
Receive request is repeated automatically
(call up of L2-RECEIVE)
6-6
Example for
Wish to transmit? (Transmit trigger bit set by the user?)
Receive enabled and "Receive viable"? (Receive enable bit set by the user
Has PAFE message or STBR error occurred?
Confirm receive request. (The program resets the
receive enable bit.)
End
Data Transmission
and bit 0 of STBR =1?)
S5-95U, SINEC L2
via PLC-to-PLC
no
no
no
no
EWA 4NEB 812 6112-02