When the “RX” command is used in Ember’s Nodetest firmware to place the device into ongoing RX (receive) mode, the serial output will display received packet information such as:

These fields can be interpreted as follows:

Here's a brief description of the results in the RX mode of nodetest:

num : Total packets received

oflo : Number of overflow errors. Stat is only updated when the next good packet is received.

seq : Sequence number received in the packet.

per : Packet error rate (missed packet percentage over the test), calculated using num and seq.

err : This is a link quality indicator (LQI) value of the received packet and represents the raw correlator error output from the radio (derived from the chip error rate during the demodulating of packets in the radio’s DSSS PHY).

lqi : This is the calculated link quality given the LQI value (from previous column) of received packet. This gives an indication of link reliability by translating the chip error rate (where higher value represents more error) into a quality measurement (where higher value represents a better link). Value of 255 (0xFF) represents a link with no significant margin of error.

rssi : Receive signal strength indicator (RSSI) value of received packet, given in dBm as a signed 8-bit value.

ed : Energy detect value (similar to RSSI but expressed in a manner as required for IEEE 802.15.4 MAC compliance testing)

gain : Receiver gain value (in dBm)

status : Frame status

time : Sync time (on an arbitrary time base, not related to any RTC; used internally by the PHY for chronological ordering of received packets)

fp : State of frame pending bit in MAC acknowledgement (1 = set, 0 = not set)

length : Length of packet payload

If you need a deeper explanation of one or more of these fields, please contact Ember ZigBee Support for further assistance.