Switching Frequency And Latency - ABB Wireless Proximity Switches Planning And Installation Manuallines

Planning and
Installation Guidelines
V 6 Technical Description

2.10 Switching Frequency and Latency

Wireless Proximity Switches / Issue: 09.2004
The input module and the communication modules communicate with each other via the air
interface.
Due to this communication and the following processing in the input module and fieldbus
connection (FieldBusPlug), certain delays occur.
Principle
st
1 proximity change is transmitted
2 nd proximity change is stored, to be transmitted as soon as 1
3 rd proximity change -> error message
Air Interface Latency
5 – 20 ms
Overall Latency
(sensor head -> signal available at fieldbus):
typical ~
99,9% of the events
max. (worst case)
(for single events in case of heavy disturbance)
Independant of number of sensors used
Min. Pulsewidth
for signal on fieldbus
-> corresponds to typ. switching frequency of 25 Hz
(worst case: min. switching frequency of 15 Hz )
BUT: Restrictions to ≤ ≤ ≤ ≤ ≤ 5 events/s (proximity changes /s)
due to energy availability in worst case spots.
Typical timing patterns can be seen in fig. 2.7
1 sec
1 2 3
1 2 3
5 changes / sec
Fig. 2.7: Timing pattern
17ms
20ms
34ms
~20ms
1 sec
4 5 1 2 3 4
4 5 1 2 3 4
5 changes / sec
st transmission is finished.
5 1
Target change
Signal on the fieldbus
5
Target change
min. 20 ms
Signal on the fieldbus
Planning and Installation Guidelines 21