Lenze EPM−T9XX Modular system - Manual (Page 178)

Transmitting process data
Process data transmission mode
8
Networking via system bus (CAN)
8.3
8.3.4
L
8.3−4 EDSPM−TXXX−9.0−11/2009
A special telegram, the sync telegram, is required for synchronisation when cyclic
process data are transmitted.
The sync telegram must be generated by another node. It initiates the
transmission for the cyclic process data of the I/O system I/P20 and at the same
time triggers data acceptance of cyclic process data received in the I/O system
IP20.
1.
PDO1-TX PDO1-RX
2. 3. 4.
 
epm−t111
Fig. 8.3−1 Synchronisation of cyclical process data with the help of a sync telegram
(asynchronous data not considered)
 Sync telegram
1. After receiving a sync telegram, the I/O system IP20 transmits the cyclic
process output data (PDO1−Tx) if "sync−controlled transmission" is active.
2. Once the transmission is completed, the I/O system IP20 receives the cyclic
process input data (PDO1−Rx).
3. The data is accepted by the I/O system IP20 with the next sync telegram if
"sync−controlled reception" is active.
4. All other telegrams (e.g. for parameter or event−controlled process data) are
accepted asynchronously by the I/O system IP20 after transmission.
Sync telegram for cyclic process
data
Transmission sequence