Technical data

9.1 Basics of Data Transmission with Global I/Os
This section describes the functions of the global I/Os from the point of view
of the CPU control program.
➣ Data exchange via I/Os
➣ How the data transmission functions
➣ Updating the I/Os with GP
In data transmission with global I/Os the data exchange takes place using
the I/Os of the SIMATIC PLC, as follows:
➣ The data for transmission are assigned to the output area of the I/Os in
the control program.
➣ The received data are stored in the input area of the I/Os.
➣ Transmitted and received data can be processed with STEP 5
operations.
The term "global I/Os" conveys the fact that part of the I/O area of a
programmable controller is not assigned "locally" to the corresponding input
and output modules but is "globally" available to all programmable
controllers on the L2 bus.
➣
Data for transmission via the output area
➣
Received data via the input area
All I/O bytes via which you want to transmit and all I/O bytes via which you
want to receive must be designated as I/Os. To do this, you reserve I/O
areas of each station taking part in the GP communication for GP using the
COM.
B8976060/02 Communication with Global I/Os
9 - 3 Volume 1