Technical data

The following diagram illustrates how the FREE mode functions for input
bytes.
Explanation of Fig.11.6:
The input byte information received from the L2 bus when processing the
DP polling list, is transferred to the input area of the CP after each DP data
exchange is completed.
Following the "update PII" function at the beginning of each CPU program
cycle or using direct access (for example, LPY) to the input bytes, the
received data can be processed further in the user program.
In the FREE mode, the DP polling list processing cycle of the CP alone
decides when the data received from the L2 bus are transferred to the input
area of the CP.
PLC
Program
Input
area
PY1 : 4
Data information
transmitted on
the L2 bus
nth processing
of the DP polling
list
(n+1) processing
of the DP polling
list
PY1 : 9
PY1 : 9
L PY 1
PY1 : 1
mth PLC cycle
(m+1). PLC cycle
PY1 : 4
PY1 : 9
L IB 1
L IB 1
L IB 1
in CP
Fig. 11.6 CP 5430 TF/CP 5431 FMS Receives from L2-DP Slave
B8976060/02 Distributed I/Os (DP)
11 - 13 Volume 1