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January 15, 2013

Digi had fixed the issues with the TCP/IP stack in the last post.  I had found some time and wanted to get PowerMeter working wirelessly, using the XBEE Module.  I wanted to use a DNS Server to do domain name resolution so I don’t have to hard code an IP in.  My web servers IP could change. Problem is, the DNS Results from standard DNS Servers would CRASH the Xbee Module. Here is my ticket I submitted.


Case Id Number: 1344839
Date Created: 09/06/2012
Status: Closed – Resolved
Product: XBee Wi-Fi
Operating System: Windows XP
Original Summary:
Product Group: Any Product
Product: XBee Wi-Fi Modules
Os: Not Applicable Not Applicable
Driver/Firmware: 102D
Serial Number: 23XXXXXXA
Problem: XBEE seems to “”crash”” after receiving results specifically from a DNS Server. (not sure why…)
The XBEE will not receive any other UDP traffic until the XBEE SRC port is changed. (either via ATC0 Command, or Modem Configuration Writing)

UDP Transmission works fine otherwise.

DST Addr: (DNS Server)
DST PORT: 0x35 (53)
SRC PORT: 0xBEF6 (48886)

PC01 is
PC02 is

if PC01 sends UDP traffic to XBEE to port 0xBEF6 it appears in XBEE’s Terminal. If XBEE communicates to (successful).. however, data is never properly returned to XBEE Terminal. At this point any other data from PC01/PC02 to XBEE is not received until XBEE changes port.

This is specifically caused by the returned data from the DNS Server. I can utilize 2 PCs and the XBEE sending/receiving data just fine. Not sure if the specific packet from a DNS Server crashes it. My Query Data packet sent to the UDP Server…


Also interesting that while researching this issue, someone has noted the similar result in his code. Near the bottom is
// DNS lookup
// *** Note: wifi is turned off when XBee send/recv the port 53 udp packet.
// XBee wifi –> request –> DNS server (wifi OK)
// DNS server –> responce –> XBee wifi (wifi turned off)
// why ??

I had actually purchased a different brand module which has DNS/HTTP/NTP/etc all built in to the module. It’s the WiFly RN-171. Some reference it to be the Digi XBEE WiFi Killer. I started to use it, however, it had some of its own limitations and I can’t remember exactly what issues I was running in to.  My jobs has me travel a lot, so I run in to times when I get side-tracked from my hobbies.

1/15/2013 – Ticket was closed by Digi (acknowledge problems with DNS that cannot be resolved)

After receiving mulltiple issues with DNS functionality on the current XBee WiFi module, the engineers did some more digging and found the chipset to have some DNS functionality issues that we are unable to fix.
We are, however, working on a next generation XBee WiFi that will be release in the next few months. It uses an Atheros chipset that is much more capable.

I’m not completely satisfied with their answer.  The chip does not have issues with “DNS”… the chip does not know its doing a DNS queries.. the chip just knows its participating in UDP Communication. The real big question is, what other type of UDP traffic causes this chip to have problems? What type of data causes it to crash? Those would have been some good answers as a response to my ticket.


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