Sending CoAP Block-wise requests (NCS 2.0.0)

RE: Sending CoAP Block-wise requests (NCS 2.0.0)

gc0rreiab — Fri, 09 Jan 2026 18:34:28 GMT

Did you get the block-wise functionality working as expected? Could you share a small example?

Before jumping into custom firmware development, I used the ot-cli sample to evaluate the feasibility of transmitting large payloads but my server isn’t receiving any data.

To test, I used the following command:

$ ot coap put <synthesized IPv6 address of the CoAP server> <uri> block-64 40

From the documentation, this command will transmit 40 data blocks of 64 bytes each to the CoAP server. However, no payload ever arrives at my CoAP server. The value 40 is intended to represent the number of blocks to send, with the actual payload consisting of random bytes. Is the block-wise implementation in OT-CLI working as expected?

The documentation also states:

“The block- type requires OPENTHREAD_CONFIG_COAP_BLOCKWISE_TRANSFER_ENABLE to be set.”

Do I need to enable this configuration? If so, can I do it in the prj.conf file like this?

CONFIG_OPENTHREAD_CONFIG_COAP_BLOCKWISE_TRANSFER_ENABLE=y

RE: Sending CoAP Block-wise requests (NCS 2.0.0)

AHaug — Wed, 28 Sep 2022 13:52:28 GMT

Hi,

Glad to hear you found a sample that you could guide you. I was about to suggest the OpenThread samples we have in the SDK, while we waited for an answer from our OpenThread team, but that seems to be redundant now.

I will mark this ticket as verified and close it by tomorrow, so let me know if you have any additional questions related to this ticket before then and I'll keep it open.

Kind regards,
Andreas

RE: Sending CoAP Block-wise requests (NCS 2.0.0)

Tristen — Tue, 27 Sep 2022 21:51:13 GMT

I figured out my issue. First I realized there was the CoAP CLI example (found in C:\ncs\v2.0.0\modules\lib\openthread\src\cli) which was very helpful. My bigger issue was that my block-wise callback was not properly copying memory from the local buffer into the CoAP buffer.