I am working in a design with EZSP Zigbee Gateway - NCP design(Emberznet 5.7.3). I have the Gateway as coordinator and an end device connected to it.
I have some custom implementation than ZCL messages. Whenever i send a Unicast message to EZSP, most of the time it responds with ERROR: tx 66 message, and message is not transmitted(Verified with sniffer). I have very less success rate only in getting the message being transmitted from NCP and delivered to end device. Most of the time EZSP respond with 0x66 error in 3 ~ 4 seconds. The device is actually shown in the enddevice table and neighbour table of gateway(Verified through CLI command).
What could be the reason that EZSP fails in a very short time for an end device Unicast message. Can you give suggestions on methos for any errors at NCP firmware.(I tried with latest 5.8.1 NCP firmware also and result was same.
An "Error: tx 66" is EMBER_DELIVERY_FAILED. This means that the NCP was not able to reach the End Device. A few reasons this could have happened:
1. The End Device is asleep and did not respond with an ACK.
2. The End Device did send out an ACK, but the NCP did not hear it.
3. The NCP does not have a route to the End Device.
Basically, the message could not be delivered and the message timed out and the error was returned. There is a communication problem between the nodes. A direct capture from the NCP could show more.