Dashboard for all devices + cross-device actions

1- How can I for example, calling or read information from the second device by using the dashboard of the first device?
2- Can I in Blynk create a unified dashboard for all the devices and their GPIOs?
3- Can i do cross-device actions.


Could you please explain how I can do that

If you needs are very basic then you may be able to use Automations.

Otherwise you’ll need to use the HTTP(s) API, like this…

You need to have one “master” device that has a Blynk dashboard and widgets that display data that will come from several “slave” devices.
If you want to control these slave devices from your master dashboard you can do that too, but I’d start by getting the data display working initially.

When you create the Master device in Blynk you’ll have an auth token for this device.
The slave devices will send data to the master device using the HTTP(s) API, as shown in the examples I linked above.

When you send data to a virtual pin on the master device (from one of the slave devices) it will update the datastream value for that pin, automatically updating any display widgets at the same time.

If you want to control one or more of the slave sevices then they will need Blynk auth tokens of their own (so will need to be set-up as Blynk devices). You’ll then use control widgets (such as switches, sliders etc) on the master device to send commands to the slave devices. You’ll do this in the code running on the master device. When a control widget value changes it will trigger the BLYNK_WRITE(vPin) callback and you’ll use this to trigger the HTTP(s) API to send the value to the slave device.