feat: complex / combine measurements

[wilbersl]

Pull Request Description:

This pull request introduces the creation of complex / combined Measurements to the Modbus plugin, designed to reduce unnecessary data traffic to the cloud. These changes enable users to prioritize high-volume data cloud resource usage for static or infrequently changing data points. This Feature works hand in hand with the on-change keyword to ensure sending fewer measurements with only the needed data.

Motivation

I use thin-edge with my own modbus poller and complex / combined measurements for some time now and want to switch to the official plugin.
Inline with my issue

Features Implemented

The feature generally opt-in, devices who currently use this plugin won't change their behavior. It can be activated on a global level as well as on a per device level, opt-out is also possible per Device.

How it Works: The plugin checks for an optional combinemeasuerments key within the modbus configuration or a device's configuration in the modbus.toml / devices.toml file. When generating the measurements this Key is checked in the Priority 1st Device | 2nd Global . If it is absent in the device, the plugin falls back to the global and if it is absent there it's off, ensuring full backward compatibility.

Example Configurations

Test modbus.toml with feature active:

[modbus]
pollinterval = 5
loglevel = "INFO"
combinemeasurements=true # if not set equals false; 

[thinedge]
mqtthost= "127.0.0.1"
mqttport = 1883

Test devices.toml can still be used to opt-out single devices:

[[device]]
name = "mock_battery1"
address = 1
ip = "127.0.0.1"
port = 502
protocol = "TCP"
combinemeasurements=false # Overrides global setting;

[[device.registers]]
number = 0
startbit = 0
nobits = 16
signed = false
multiplier = 1
input = false
measurementmapping.templatestring = '{"power": %%}'

[[device.registers]]
number = 100
startbit = 0
nobits = 16
signed = false
input = false
measurementmapping.templatestring = '{"error_flag": %%}'
on_change = true # new update

[[device]]
name = "mock_battery_2"
address = 1
ip = "127.0.0.1"
port = 41502
protocol = "TCP"
#combinemeasurements=false # No Override uses the global option

[[device.registers]]
number = 0
startbit = 0
nobits = 16
signed = false
multiplier = 1
input = false
measurementmapping.templatestring = '{"power": %%}'

[C8Y-Mario]

Thanks for this PR, as well! I think the feature makes sense - I was looking into leveraging bulk creation of Measurements, but this makes also sense for a lot of use cases.

[C8Y-Mario]

Seems good to me

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
15	0	0	15	100	35.8767s

Passed Tests

Name	⏱️ Duration	Suite
Device should support the operation c8y_ModbusConfiguration	0.138 s	Device
Set values via c8y_ModbusConfiguration Operation	2.444 s	Operation
Poll rate and transmit rate should be updated for the Device	0.264 s	Operation
Poll rate and transmit rate should be updated on the Device	2.436 s	Operation
Device should support the operation c8y_ModbusDevice	0.139 s	Device
Device should have installed software tedge-modbus-plugin	0.175 s	Debian
Service should be active	2.435 s	Debian
ReInstall Modbus Plugin	25.947 s	Debian
Device should have the fragment c8y_ModbusConfiguration	0.275 s	Device
ChildDevice TestCase1 should be created	0.267 s	Device
ChildDevice TestCase1 should have the fragment c8y_ModbusDevice	0.675 s	Device
Service tedge-modbus-plugin should be enabled	0.138 s	Device
ChildDevice TestCase1 should have a Test.Int16 Measurement	0.274 s	Telemetry
ChildDevice TestCase1 should have a Test.Float32 Measurement	0.270 s	Telemetry
ChildDevice TestCase1 should have Alarms of type TestAlarm on Coil Value 1	0.001 s	Telemetry

[reubenmiller]

@wilbersl Approved. Thanks again for the nice addition