LON • 105
Modular I/O System
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4.5.1 Data exchange via network variables
An example (source [2]):
Let us assume that node 1 (sensor) is a temperature sensor. A network output
variable ‘temperature’ (NVO_temperature) is defined and assigned the current
temperature value measured.
Fig. 4-1: Example for a network output variable
For another node 2 (actuator) intended to control a heat radiator, a network in-
put variable ‘temperature’ (NVI_temperature) is defined which is assigned the
current temperature value from the sensor node via the network.
Fig. 4-2: Example for a network input variable
The definition of these NV's is made independent from one another.
Binding now links these two network nodes together. The current value is
automatically transferred by node 1 to node 2 via the network.
Fig. 4-3: Example for the data exchange of the network variables
The temperature sensor signals a temperature change, and the logically as-
signed controls correspondingly switches the heat radiator on or off.
4.5.2 Standard types of network variables
The so-called standard types of network variables (SNVT's) are invariably
pre-defined types of variables for network variables. Almost any size occur-
ring in automation tasks have been standardised. The ensure an automatic un-
derstanding of network nodes originating from different programmers.