Lenze EPM−T9XX Modular system - Manual (Page 262)

Communication
Cyclic data transfer
10
Networking via PROFIBUS−DP
10.3
10.3.2
L
10.3−2 EDSPM−TXXX−9.0−11/2009
10.3.2 Cyclic data transfer
The data communication with PROFIBUS−DP−V0 includes cyclic diagnostics as
well as cyclic process data and parameter data transfer.
Master
(DPM 1)
Slave
buffer receive
Communications
processor
PA
buffer send PE
0 1
 ‚
epm−t228
Fig. 10.3−1 DP cycle and cycle of backplane bus
0 Backplane bus with transmit and receive buffer
1
Input / output modules
PO: process image of outputs
PI: process image of inputs
 PROFIBUS cycle
‚ Backplane bus cycle
During a backplane bus cycle
l the input data (PI) on the inputs is collected and transmitted to the transmit
buffer (buffer send),
l the output data (PO) of the receive buffer (buffer receive) is written to the
outputs.
During a PROFIBUS cycle, the master successively addresses all its assigned
slaves with a DataExchange. During a DataExchange, the memory areas assigned
to the PROFIBUS are transmitted.
l The data of the PROFIBUS input area is transmitted to the receive buffer
(buffer receive).
l The data of the transmit buffer (buffer send) is transmitted to the PROFIBUS
output area.
Backplane bus cycle
PROFIBUS cycle