Downlink Example ACK

[BlairAllegroTech]

Would you be able to add to the downlink example an example (preferably the NodeJS example) of the expected Downlink ACK response.

I have an Oyster device which takes several configuration messages. I am expecting an ACK to come back with ack:true after sending a downlink message, before i send the next configuration downlink message.

Then finally when all configurations are sent i would respond to the last ACK with a 204 (No Content) do indicate that there are no more configuration messages ?

I could have completely misunderstood the documentation but an example would be really help full!!

Much Appreciated

[nicolsc]

Hi @BlairAllegroTech

In fact it seems you would need to build your own applicative acknowledgement mechanism to achieve this.

By default, what happens is:

• Device A sends an uplink message, with the ack flag set to true. It will switch to RX mode a few seconds after transmission, after emitting this message
• Sigfox backend receives the message, and forward the downlink request to your application server using the DATA > BIDIR callbacks (if configured that way)
• Your application server responds within 10 secs either with a 204 No Content or a 200 OK and the appropriate JSON body
• If your reply is 200 (+valid JSON) ; the Sigfox backend will allocate this downlink message to the appropriate base station
• This base station will emit this message, this emission will trigger the SERVICE > ACK callback
• The device will receive the message, and automatically send an Out Of Band System message. This OOB frame will not trigger any callback, and may not be visible to you as a customer depending on your access rights.

Long story short : The only "downlink delivery" callback that you can subscribe (SERVICE>ACK) will notify you that the message has been emitted, which doesn't mean for sure that it was received by your device.

In this extensive blog post, @disk91 gets into the details and suggest a way to set up your own "downlink reception confirmation" mechanism https://www.disk91.com/2017/technology/sigfox/sigfox-downlink-in-details/