Endless scanning sometimes.

[priyanka-Sadh]

Using following version
"react-native": "0.62.2",
"react-native-ble-plx": "^1.1.1",
I want to know reason of below scenario:

When Mobile app is in connected status with ble device,
and I turn off the device app goes to disconnected mode and re-scan and then connect. (I repeat this)
It happens regular 2-3 time successfully, after this sometime app goes to endless scanning (Scanning...) mode so in this case I have to kill and re-launch the app.

And sometime (after 2-3 time) it continuously says BleError : can not start scanning operation
so in this case I have to kill and re-launch the app or need to again turn-off or turn on the device.

My code below
this.manager.startDeviceScan(null,{ScanMode : "Balanced" }, (error, device) => { console.log("Scanning..."); if (null) { console.log('null'); return; } if (error) { console.log("Error in scan=> "+error) this.scanAndConnect() return } if(device.name == 'mydevice'){ this.manager.connectToDevice(device.id, {autoConnect:true}).then((device) => { (async () => { //listener for disconnection device.onDisconnected((error, disconnectedDevice) => { console.log('Disconnected ', disconnectedDevice.name); this.scanAndConnect(); // to start scanning again }); })(); }); } })

may I know the reason or any mistake if I made here in code ?

[dariuszseweryn]

You do not stop the scan it seems?

[priyanka-Sadh]

I do just after once mydevice got found. Sorry for above code mistake.
this.manager.startDeviceScan(null,{ScanMode : "Balanced" }, (error, device) => { console.log("Scanning..."); if (null) { console.log('null'); return; } if (error) { console.log("Error in scan=> "+error) this.scanAndConnect() return } if(device.name == 'mydevice'){ this.manager.stopDeviceScan();this.manager.connectToDevice(device.id, {autoConnect:true}).then((device) => { (async () => { //listener for disconnection device.onDisconnected((error, disconnectedDevice) => { console.log('Disconnected ', disconnectedDevice.name); this.scanAndConnect(); // to start scanning again }); })(); }); } })

[priyanka-Sadh]

here is the error {console.log(JSON.stringify(error));}
[Sat Jun 06 2020 21:26:23.869] LOG {"message":"Cannot start scanning operation","errorCode":600,"attErrorCode":null,"iosErrorCode":null,"androidErrorCode":null,"reason":"Undocumented scan throttle (code 2147483646), suggested retry date is Sat Jun 06 21:26:21 GMT+05:30 2020","name":"BleError","line":26121,"column":28,"sourceURL":"http://localhost:8081/index.bundle?platform=android&dev=true&minify=false"}

[dariuszseweryn]

You scan too often. Android allows only 5 scans in every 30 seconds window.

[priyanka-Sadh]

same is for ios ?

[dariuszseweryn]

No

[priyanka-Sadh]

hmm, I checked with stop watch, continuous =>scan,connect,disconnect (Repeat) work for 2 time only, in 3rd round it goes endless scanning-> {"message":"Cannot start scanning operation"} and this error.

Check with stopwatch 3rd round was under 30seconds window.

[priyanka-Sadh]

Full working file
`import React,{Component} from 'react';
import {BleManager} from "react-native-ble-plx";
import {PermissionsAndroid, Platform} from 'react-native';

export default class Ble_test extends Component {
constructor() {
super();
if (Platform.OS === 'android') {
PermissionsAndroid.request(PermissionsAndroid.PERMISSIONS.ACCESS_COARSE_LOCATION)
.then(granted => {
if (granted !== 'granted') {
console.log('BLUETOOTH denied')
}
else {
this.initializeManager();
}
})
} else {
this.initializeManager();
}

}

initializeManager() {
    this.manager = new BleManager({
        restoreStateIdentifier: 'testBleBackgroundMode',
        restoreStateFunction: bleRestoredState => {
        }
    });
    const subscription = this.manager.onStateChange((state) => {
        if (state === 'PoweredOn') {
            this.scanAndConnect();
        }
    }, true);
}

scanAndConnect() {
    this.manager.startDeviceScan(null, null, (error, device) => {
        console.log("scanning");
        console.log(device);
        
        if (error) {
            console.log(JSON.stringify(error));
            this.scanAndConnect()
            return
        }
        
        if(device.name == 'TAPP_noljal'){
            console.log("found ", device.name);
            this.manager.stopDeviceScan();
            this.manager.connectToDevice(device.id, {autoConnect:true}).then((device) => {
                    (async () => {
                        console.log("connected to ",device.name);
                        //listener for disconnection
                        device.onDisconnected((error, disconnectedDevice) => {
                            console.log('Disconnected ', disconnectedDevice.name);
                            this.scanAndConnect();
                        });
                        
                    })();
                })
     }
    });
}

render() {
    return null;
}

}`

[dariuszseweryn]

Correct me if I am wrong but returning an error is not an endless scan? Is it? It is an error while starting a scan?

[priyanka-Sadh]

Yes it's an error while scanning,
So I am calling this.scanAndConnect() again if error comes.

[dariuszseweryn]

Mhm... And what do you recon then?

[priyanka-Sadh]

Yes, I want reconnect then with same device.
Because user who is using BLE device can regular switch off and switch on the device. This can be a scenario.
So I call scan method again even if error found in single scan

[dariuszseweryn]

There is nothing you can do. There may be only that many scans during a specific time frame. You have to deal with it

[priyanka-Sadh]

Ahh, Okay,
Well Thanks for responding so fast. I am closing it now, If in case further scanning query I will reopen it.
I don't know if i am referring wrong here for replying on #669 please