ABB EDS500 Series Function Manual page 64

Serial Tunnel
RX
Sample
IP Packet
TX
Figure 21: Interruption in the serial data stream
The data transmission as a whole has to be delayed to avoid interruptions at the tunnel exit.
Like this it is ensured that the following data is already available and can be issued without
gap. A DCD lead time is set at the serial interface for this purpose (refer to Chapter 2.20.2,
"Transmission Parameters of the Interface").
It does not matter if the DCD signal of the serial interface is actually used. The DCD lead
time takes care that the data transmission is delayed at the tunnel exit and therefore stays
coherent.
1.5 times the sampling frequency can be assumed as a guide line for DCD lead time. Possible
jitter in the transmission time of Ethernet/IP packets can be buffered in this way.
RX
Sample
IP Packet
TX
Figure 22: Avoid interruptions with lead time
Caused by jitter in the packet runtimes through the Ethernet/IP network as well as different
baud rates at the tunnel entrance and exit, can cause that a serial telegram arrives at the
tunnel exit while the previous telegram is still being sent or the DCD signal is still active e.g.
due to a set DCD delay.
This causes that the DCD lead time is not applied as the DCD signal is already active and the
data is sent directly (as soon as possible).
Pauses that existed between the telegrams at the tunnel entrance can be eliminated by this at
the tunnel exit. This can disturb the serial communication.
To ensure pauses at the tunnel exit, a pause detection can be set for the tunnel entrance.
The pause detection forces the DCD signal to be switched off. Like this, the set DCD lead time
is kept between two serial telegrams. Pause for the detection and DCD lead time should be
set to the same values.
Commands for the configuration of enhanced tunnel parameters
< s e t i n t e r f a c e { c o n s o l e 0 | c o n s o l e 1 } s a m p l i n g { 1 - 1 2 0 } >
< s e t i n t e r f a c e { c o n s o l e 0 | c o n s o l e 1 } d c d - s e t u p { 0 - 2 5 5 } >
< s e t i n t e r f a c e { c o n s o l e 0 | c o n s o l e 1 } p a u s e - d e t e c t i o n
{ 0 - 2 5 5 } >
64
1 2 3 4 5 6
1 2 3 4 5
1 2
Gap
1 2 3 4 5 6
1 2 3 4 5
Setup time 30 ms
6
3 4 5 6
6
1 2 3 4 5 6
1KGT151021 V000 1
Functions