Sending Messages II.
Description
Estimated time required: 10 minutes
Following the tutorial below, you can send Non-acknowledged messages in an already existing NeoMesh network.
Required hardware
- 2 NeoCortec Evaluation boards
- 2 USB cables
Required software
- NeoCortec Demo_App (Supplied on your USB card)
Sending Non-Acknowledged messages
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You should have 2 instances of the “Demo App” from the previous tutorial open and connected to the NeoCortec evaluation boards 0x10 and 0x20. A detailed description of the “Demo App” is available here.
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This time we want to send the payload data "102030" through the network without a returned acknowledge message. Copy the message to the "Payload hex" box and check, if the "Package type" is set to Non-Acknowledged. When you are done with the changes, the settings box should look like this.
- Leave other options unchanged and hit the “Send” button.
- Watch the sent package arrive to the addressed node and see, that this time there is no Acknowledge message at the initiator node.
Sender node:
Receiver node:
In a NeoMesh network all nodes can send and receive Non-Acknowledge messages.
“Ooops that didn’t work” - Let us take a look at the difference between the Acknowledged message from the previous tutorial
and the Non-Acknowledged messages. You can see the raw message for yourself on the “Demo App” window, under the “Raw” column in the “Device communication log” section.
- Please note, that the NACK message has two extra bytes, called the "Sequence number". For your convenience, these bytes are extracted to the "Seq" column. The "Sequence number", consisting of 12 bit shall be handled by the application layer, and it's purpose is
to distinguish between new Non-Acknowledge messages and duplicates of received older NACK messages. (What is the sequence number? )
You can prepend the sequence number through the "Demo App", by typing the desired number into the "Sequence Nr.:" field, next to the "Send" button.