C1120 S5 to II/O Lightbus Interface
Beckhoff II/O-Lightbus System
Date 27.06.97
Version 2.1
Page 11 of 52
By setting the "Free Run" option to "1" in the equivalent mask, the inputs of the II/O-Lightbus
System are read asyncronously to the PLC- process image at maximum II/O Lightbus
communication refresh rate. The pageswitch mechanism displayes the newest process image
memory page to the PLC.
Entering a “ 1” in the field PLC IRQ Frame causes the C1120 to send an extra control and
interrupt message frame for triggering a local process image cycle on the intelligent peripheral
modules. Those message frames are appended to the process data message frames.
The current page address of the C1120 is entered in the Page Number field.
String communication is used for communicating with intelligent peripheral modules. It can
be used, among other things, for configuring the modules. The data packages (strings) are
transmitted to the C1120 by way of the page frame.
The field Transmit Basis is for entering the page frame offset for the strings being sent. It
should be noted that starting from the offset, 2 bytes are reserved for the handshake between
PLC and C11220. The actual string is entered starting at the 2.
The field Receive Basis is for entering the page frame offset for the strings being received. It
should be noted that starting from the offset, 2 bytes are reserved for the handshake between
PLC and C11220. The actual string is entered starting at the 2.
The field Maximum String Length is for entering the maximum permissible length of the
strings.
The purpose of the fast communications channel is for improved process synchronisation
during multi-processor operation (see also “ Fast Communications Channel” ).
Entering a “ 1” in the Activate field enables the fast communications channel (see also “ Fast
Communications Channel” ).
Entering a “ 1” in the field IRQ Frame causes the C1120 to send an extra control and
interrupt message frame for triggering a local process image cycle on the intelligent peripheral
modules assigned to the process channel. Those message frames are appended to the process
data message frames.
