Install Guide

SENSIT SYSTEM | MANUAL
Frequently Asked Questions
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NETWORK & COMMUNICATION
How much events can a SENSIT node store?
Every SENSIT node is capable of storing 32 events in its internal memory.
What causes the latency of a SENSIT sensor?
The latency is built up out of different aspects;
• The measurement interval;
The interval the SENSIT sensor verifies it status changed, default set at 1
second.
• The overdrive filter;
The overdrive delay set in the SENSIT sensor is by default set at 8 seconds.
• The number of hops;
The number of hops a message needs to arrive at the SENSIT Gateway,
every hop takes about 2 seconds.
• Passive collisions;
In a busy car park multiple SENSIT sensors want to transmit their status
change message simultaneous, which might create passive collisions. In
order to reduce this we advise to ensure that each SENSIT sensor can at
least communicate with 2 Relay Nodes offering multiple communication
paths.
Example with default settings and without passive collisions:
The magnetic and optical sensor measures every second if the status of the
bay is changed. The overdrive filter waits 8 seconds before it transmits the
event. In this example the event is transmitted via 2 Relay Nodes; first from
the SENSIT to the nearest Relay Node and then from this Relay Node to the
Relay Node close to the SENSIT Gateway and finally from this Relay Node to
the SENSIT Gateway. The total (worst-case) time needed is:
Measurement + overdrive + SENSIT→RN + RN→RN + RN→ SENSIT Gateway
= 1+8+2+2+2 = 15s
Example with default settings and with one passive collision:
The magnetic and optical sensor measures every second if the status of the
bay is changed. The overdrive filter waits 8 seconds before it transmits the
event. In this example the event is transmitted via 2 Relay Nodes; the
sequence of transmitting the messages is the same as in the example above
but now a collision occurred in the first transmission; another SENSIT
transmitted an event at the same time to the Relay Nodes. The total (worst-
case) time needed is now:
Measurement + overdrive + collision + SENSIT→RN + RN→RN + RN→
SENSIT Gateway = 1+8+10+2+2+2 = 25s
How many seconds does an event message take in general?
The transfer time is depending on the number of hops and if passive collisions take
place. A collision free transfer via one Relay Node takes less than 5 seconds, for
every extra hop add 2 seconds. For a busy parking lot take into account at least 10
seconds extra for possible passive collisions.
Is the package number always increasing per SENSIT?
Yes, the package number is automatically increased in sequence number per SENSIT
and the message is unique based on a combination of SENSIT ID number and
package number.