can't read from readable Characteristic

[Matrix-Zhang]

D/com.polidea.flutter_ble_lib.FlutterBleLibPlugin( 7591): on native side observed method: readCharacteristicForIdentifier
E/flutter ( 7591): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: BleError (Error code: 2, ATT error code: null, iOS error code: null, Android error code: null, reason: null, internal message: null, device ID: null, service UUID: null, characteristic UUID: null, descriptor UUID: null)
E/flutter ( 7591): 

use the monitor is ok

[mikolak]

Error code 2 means operation cancelled. I think you might've passed the same transaction ID to two operations.

[Matrix-Zhang]

Error code 2 means operation cancelled. I think you might've passed the same transaction ID to two operations.

Okay, i think the transaction id is session id....

after i remove the transaction id, new error comes

E/flutter (24967): [ERROR:flutter/lib/ui/ui_dart_state.cc(166)] Unhandled Exception: BleError (Error code: 3, ATT error code: null, iOS error code: null, Android error code: null, reason: GATT exception from MAC address 5B:14:86:24:98:64, with type BleGattOperation{description='CHARACTERISTIC_READ'}, internal message: null, device ID: null, service UUID: null, characteristic UUID: null, descriptor UUID: null)

[mikolak]

3 is operation timeout. https://github.com/Polidea/FlutterBleLib/blob/develop/lib/error/ble_error.dart

This library is based on our React Native BLE library and some things are directly translated from there. You can check out what the errors mean here: https://polidea.github.io/react-native-ble-plx/#bleerrorcode

I need to add docs to those error codes here...

[Matrix-Zhang]

3 is operation timeout. https://github.com/Polidea/FlutterBleLib/blob/develop/lib/error/ble_error.dart

This library is based on our React Native BLE library and some things are directly translated from there. You can check out what the errors mean here: https://polidea.github.io/react-native-ble-plx/#bleerrorcode

I need to add docs to those error codes here...

why timeout? if i remove the Characteristic's read method, just listen on Characteristic's monitor, the data will received....

[mikolak]

I don't why, I haven't seen your code. 🙂 If you're not monitoring, does the read succeed?

[Matrix-Zhang]

I don't why, I haven't seen your code. 🙂 If you're not monitoring, does the read succeed?

if i not monitoring, the read timeout,

the code just like:

write("1234") ; //send to peripheral success, peripheral will received the data
read(); // read from peripheral timeout, if change to monitor, data coming

[Matrix-Zhang]

if android read from ios, the error code is 402

session error: BleError (Error code: 402, ATT error code: null, iOS error code: null, Android error code: 241, reason: GATT exception from MAC address 7B:B1:06:39:0D:F1, status 241 (UNKNOWN), type BleGattOperation{description='CHARACTERISTIC_READ'}. (Look up status 0xf1 here https://android.googlesource.com/platform/external/bluetooth/bluedroid/+/android-5.1

[mikolak]

Can you check the permissions on your characteristic? (isReadable, isWritable, etc.)

[Matrix-Zhang]

Can you check the permissions on your characteristic? (isReadable, isWritable, etc.)

yes, i have checked it already, the characteristic is readable