Timing - Leuze electronic DDLS 200 Technical Description

Ethernet

10.6.2 Timing

Sequence diagram
Assumption: the host computer wants to transmit a run command to PLC via optical data transmission
path (see figure 10.10).
Data completely transferred to memory
Start of serial transmission to main board,
Œ
data is optically transmitted
µC
processing
Data transmitted serially to main board and optically at 2Mbit/s
Data is sent from
host computer
Figure 10.11:Typical Ethernet telegram structure
Description of time segments
Pos. Description
DSP processing time for preparing
➀
data to be sent via optical interface
Sending data via optical interface
➁
with 2Mbit/s
Delay caused by optical conversion
➂
and light propagation time
DSP processing of data between
➃
optics and writing to Ethernet con-
troller
Data is sent to PLC
➄
58

Total delay of telegram
Time (estimated)
approx. 30µs
Number of bits in
telegram • 550ns
1.2 µs
approx. 30µs
Number of bits in the
telegram • 0.1µs at
10Mbit/s (0.01µs at
100Mbit/s)
DDLS 200
End of serial transmission
to main board
Last bit received via optics
Ž
Data in the transmit register of

Ethernet controller
DT

Propaga-
µC
Propaga-
Telegrams which are still being
sent or still in memory may delay
further processing
Signal is delayed by approx.
2.2 µs 3.3ns per meter of optical trans-
mission path
Telegram transmission
completed
Telegram is sent
to PLC
Remark
Leuze electronic