Is the timing of Transmit Status (0x8B) different between XbeePro and XBee3?

  1. Are Transmit Status messages de-prioritized or sent with different logic when using XBee3? It almost seems that the XBee Pro Transmit status is sent when the message transmission is complete rather than when the receiver acknowledges receipt of the message.

  2. Could CCA help with a network that tends to burst detection data over a short period?

I’m seeing round trip times between Transmit and Transmit Status that are consistently 2-3X longer for XBee3 vs. a similar network of XBee Pro devices.

My setup/observations:
Running Digimesh firmware (8173-XBP, 3004-XB3)
6 sensors + 1 base receiver (Either all XBee3 or all XBee Pro.)
Sensors responding to a detection that can be <20ms time differential between sensors.
Round trip times of 100-150ms when network consists of only XBeePro.
Round trip times of 200-600ms when network consists of only XBee3 devices.
Setting NN to 10 (0xA) improves XBee3 performance slightly. (150-400ms RTT)

The XBee 3 is a faster processor than the previous processes used in the XBee product lines.

Adjusting the CCA could help as I don’t know which XBee product you are referring to as it may calculate it differently.

I turned on CCA and performance did improve somewhat.

The documentation says that “If the device detects energy above the CCA threshold, it will not transmit the packet.”

This implies that the responsibility of re-transmitting is the sender’s responsibility.

Is this the case, or does the device attempt to re-transmit after some delay?

No, that is correct. It is up to the device connected to the XBee to re-transmit the packet.