# BLE cannot communicate via transmit channel **URL:** \ **Category:** BLE / BlueTooth\ **Created:** [October 12, 2022, 11:57am UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804 "2022-10-12T11:57:40Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![yurgen](https://avatars.discourse-cdn.com/v4/letter/y/5daacb/32.png) [@yurgen](https://community.thunkable.com/u/yurgen)\ **Post date:** [October 12, 2022, 11:57am UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/1 "2022-10-12T11:57:40Z")
Hello everybody! Pls help me to understand very strange BLE behavior. I have a device with BLE module. First of all, the device works good with other APPs, for example, nRFConnect. But when I try to use my device with Thunkable Live test, it can work ONLY if I firstly connect it to nRFConnect. To be more detailed it can be connected, I see the ID of my device. But the Read String doesnt work until I run nRFConnect and connect my device in it. Its very strange for me, I dont understand how this is possible. ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/d/8/d811f8daa7b93a94c06d61c565f5caa4c5d46b76.png) ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/3/6/3682a4e09e5e585e8196252087aeaacaf0b41523.png) ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/3/3/33a098b3635e0dec04da77dc2f89a36a66fd7e05.png) ![image](https://us1.discourse-cdn.com/flex015/uploads/thunkable/original/3X/0/d/0d8cdea080b62365cd4ab56285bc2ad854bfc09b.png) Until I connect in nRFCONNECT the data cant be recieved. I downloaded APK, but the result is the same. ---
**Author:** ![muneer](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/muneer/32/75210_2.png) [@muneer](https://community.thunkable.com/u/muneer)\ **Post date:** [October 13, 2022, 4:32pm UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/2 "2022-10-13T16:32:48Z")
Thunkable can only use the **READ** attribute of the `characteristic`. It cannot use the **NOTIFY** attribute. ---
**Author:** ![yurgen](https://avatars.discourse-cdn.com/v4/letter/y/5daacb/32.png) [@yurgen](https://community.thunkable.com/u/yurgen)\ **Post date:** [October 21, 2022, 9:15pm UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/3 "2022-10-21T21:15:43Z")
I dont use NOTIFY in Thunkable. This is just a Characteristic`s attribute, that is set on Device side. I use Receive String in blocks. But it works only after I connect a device in any another App, for example, BLE Scanner, nRFConect, etc. Only after this, the Receive String starts working. ---
**Author:** ![yurgen](https://avatars.discourse-cdn.com/v4/letter/y/5daacb/32.png) [@yurgen](https://community.thunkable.com/u/yurgen)\ **Post date:** [October 23, 2022, 9:22pm UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/4 "2022-10-23T21:22:16Z")
I can tell you more. I made the same APP in AppInventor and it works good. And the same strange thing: Thunkable APP can do the Receive String block only if I firstly launch the AppInventor APP and connect my device in it. I cant understand how this works and why. Why Thunkable App can work only if another APP is launched and connected to my device? ---
**Author:** ![yurgen](https://avatars.discourse-cdn.com/v4/letter/y/5daacb/32.png) [@yurgen](https://community.thunkable.com/u/yurgen)\ **Post date:** [October 27, 2022, 11:09am UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/5 "2022-10-27T11:09:02Z")
Thunkable doesnt support Notify attribute of characteristic. > > > I am using Thunkable X and I need to get notified every time a variable in BLE s…tack changes. > so please add a feature so this could be possible. ---
**Author:** ![ioannis](https://sea1.discourse-cdn.com/flex015/user_avatar/community.thunkable.com/ioannis/32/146956_2.png) [@ioannis](https://community.thunkable.com/u/ioannis)\ **Post date:** [November 8, 2024, 1:12pm UTC](https://community.thunkable.com/t/ble-cannot-communicate-via-transmit-channel/2079804/6 "2024-11-08T13:12:44Z")