question

As far as I know, you can use either dbus or node-red

Personally I prefer to define a script using dbus and then to run it with crontab.

As an example of controlling relays:

#dbus -y com.victronenergy.system /Relay/1/State SetValue 1

Above command will set Relay1 ON (close contacts)

you can check if it is closed or not by issuing :

#dbus -y com.victronenergy.system /Relay/1/State GetValue

Please use dbus-spy to get all the paths for you script

As another example, here is a small script which I use to interrogate EM111 grid meter for TotalEnergy, L1 AC voltage and current:

#!/bin/bash

RE=`dbus -y com.victronenergy.grid.cgwacs_ttyUSB2_di32_mb1 /Ac/Energy/Reverse GetValue | awk '{printf("%d\n",$3 + 0.5);}'`

FE=`dbus -y com.victronenergy.grid.cgwacs_ttyUSB2_di32_mb1 /Ac/Energy/Forward GetValue | awk '{printf("%d\n",$3 + 0.5);}'`

TE=$(($FE+$RE))

echo Total Energy $TE kWh

ACC=`dbus -y com.victronenergy.grid.cgwacs_ttyUSB2_di32_mb1 /Ac/L1/Current GetValue | awk '{printf("%d\n",$3 + 0.5);}'`

echo Current $ACC A

VCC=`dbus -y com.victronenergy.grid.cgwacs_ttyUSB2_di32_mb1 /Ac/L1/Voltage GetValue | awk '{printf("%d\n",$3 + 0.5);}'`

echo Voltage $VCC V

root@ccgx:~# dbus -y com.victronenergy.system /Ac/ConsumptionOnOutput/L1/Power GetValue
443

A space a day, keeps dbus at bay.

A few more questions remain:

How's the return value after a SetValue to be interpreted?

root@ccgx:~# dbus -y com.victronenergy.system /Relay/0/State SetValue 1
0

Or here:

root@ccgx:~# dbus -y com.victronenergy.system /Buzzer/State SetValue 1
2

And how can one make sure the value set also remains set?

e.g. setting that buzzer, it blips shortly and is then off again. Haven't checked the relay, but I assume that wil lbehave the same?