ABB UniGear Series, Engineering Manual

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ENGINEERING PRO CES S BUS (S MV)
1VLG5 00007 E 5 1
SMV delay
The SMV Max Delay parameter, found via menu path Configuration/System , defines how
long the receiver waits for the SMV frames before activating the ALARM output. This setting
also delays the local measurements of the receiver to keep them correctly time aligned. The
SMV Max Delay values include sampling, processing and network delay.
Figure 69: SMV Max delay setting in PCM600
ALARM activates when two or more consecutive SMV frames are lost or late. A single loss of
frame is corrected with a zero-order hold scheme, the effect on protection is considered neg-
ligible in this case and it does not activate the WARNING or ALARM outputs.
Table 5: Topology-dependent SMV max delay setting
Number
of hops
in
network
Internal
App.delay
[
μ
s]
[50Hz]
Internal
switch
delay [
μ
s]
Store and
forward
latency
[
μ
s]
Queue
latency
[
μ
s] 1)
Additional
tolerance
[
μ
s] 2)
Theoretical
max delay
[
μ
s]
Recommended
max delay
setting [
μ
s]
2 1 746 20 24 240 80 2 112 3 150
5 1 746 50 60 600 200 2 656 3 150
10 1 746 100 120 1 200 250 3 416 3 150
15 1 746 150 180 1 800 300 4 176 3 150
20 1 746 200 240 2 400 350 4 936 4 400
25 1 746 250 300 3 000 400 5 696 5 650
30 1 746 300 360 3 600 450 6 456 5 650
1) Queue latency calculated when the port has started to send a full-sized frame (1500
bytes) before the SMV frame and the switch has been configured to prioritize SMV
2) Additional tolerance in case of long wires or disturbance in network
Default max delay setting (3 150
µ
s) can be set for most of the communication topologies.
Special attention must be focused on HSR topology when number of hops in network should
be calculated for the worst situation (HSR ring is open).