Reading status from the cloud is not working

Need Help With My Project
1

Greetings everyone, i need help with my project where i am trying to use on/off switch toggle when the esp takes a signal from the arduino, and then read a status of that on/off switch from the server with another esp8266 to do action, for example: if my train enters the station and stops, it send to the cloud that train stopped at base, then the base reads the status of this switch to open a protection sheild gate
3. Add details :
• Hardware model: esp8266
• Blynk server
• Blynk Library version 1.2.0
• using Arduino ide

[Code deleted by moderator]

2

@Salam please post your code without the bold formatting on the section you have an issue with. Bold formatting doesn’t work with code.

Posting code snippets rarely works, as it just leaves us with lots of unanswered questions.

Pete

3

sorry for the inconvenience, and thank you for the fast reply.


void setup() {
  Serial.begin(115200);

  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  Serial.println("Started.... ");
}

// in the next section, the value is not getting called from the server even when i try to print the data on serial monitor
BLYNK_WRITE(V1) {

  int pinValue = param.asInt();


  if (pinValue == 1) {
    digitalWrite(2, HIGH);
  } else {
    digitalWrite(2, LOW);
  }
}


void loop() {
  Blynk.run();


  // receive from arduino and send to cloud
  if (Serial.available()) {
    String data_rcvd = Serial.readString();
    data_rcvd.trim();

    if (data_rcvd == "Rail_1_on") {

      Blynk.virtualWrite(V1, 1);
    }

    if (data_rcvd == "Rail_1_off") {
      Blynk.virtualWrite(V1, 0);
    }
  }
}
4

You seem to be under the impression that Blynk.write(V1) will trigger BLYNK_Write(V1)

This isn’t how it works, because if it did then you could easily create an infinite loop.

You should control your digital pins directly, rather than expecting Blynk to do it for you.

You also need some pinMode commands in your void setup.

Pete.

5

I am sorry Pete, but can you explain more, i`m new to Blynk.

6

Control your digital pins in here.

Pete.

7

i`m sorry Pete, but it seems i didnt explain my problem well, my problem is the code below doesn’t retrieve data status from the cloud.
thats why it is always 0 so no change happens, and no result on serial monitor if i tried to print the result.

8

How are you changing the value of the V1 datastream?

Where are you trying to print that value?

Pete.

9

this is a received serial signal from Arduino to the esp8266 to toggle on/off relating to the received string.
and it does change automatically the switch state on the cloud, with every time esp gets a string it is compared and the status is changed
however, I am trying to recall the status of that V1 to toggle another switch that will lead to another function to be executed.

although, it is working only when i manually change the status of the switch from the cloud.
and this is my project example. this operation should be completely automated with sensors

thank you for your replies.

10

I’ve already explained that BLYNK_WRITE(Vpin) isn’t triggered by a Blynk.virtualWrite(VPin) from the same device.
This is to avoid the possibility of an infinite loop being created.

As I already said, you shouldn’t be using Blynk to trigger that other function, just trigger the function directly in your sketch when the appropriate criteria is met.

Pete.

11

Understood, but I want to trigger it from another device not the same device, can I overwrite the library or subscribe to a premium plan that will make me able to trigger the function from another device?

12

You can trigger it from another device (device B) , provided that device has its own Auth token and you use the Auth token of device A in an HTTP(S) REST API call.

Depending on your use-case and the frequency of these data transfers, you may also be able to use Automations.

Pete.