SmartSwarm 300 Series
:
80
The following example shows a numeric register that ramps monotonically from 0, incrementing by 1 on each
Modbus master access. The red annotations show when MQTT publishes will be triggered, assuming that a Change
rule is applied, with “Change by” = 10%.
●
If the register has not been seen on the bus before, then the first value of 0 is considered to be a change
of 100%. So the value of 0 triggers a publish.
●
If the current enriched register value is 0, then any non-zero value is considered to be a change of 100%.
So the value of 1 triggers a publish.
●
The next change from 1 to 2 represents a 100% change, which is greater than 10%.
●
A change from 2 to 3 represents a 50% change, and so on.
●
A change from 10 to 11 represents a 10% change, which is not greater than 10%. The value of 11 does not
trigger a publish.
●
As the enriched register value increases further, the absolute change of 1 becomes smaller in percentage
terms. No further MQTT publishes are triggered.
For a slave waveform like this you probably want to specify an
absolute
change. See the Delta event type below.
10.2.3 DELTA
Trigger when the enriched register value changes from the last
published
value.
This event is only applicable to Input Registers and Holding Registers, not Discrete Inputs and Coils.
It is only applicable to numeric data types, and the counter data type:
It is only applicable to numeric data types, and the counter data type:
Inputs,
Coils
Input Registers,
Holding Registers
ENUM
Numeric
STRING
COUNTER
