Tuesday, February 14, 2017

Recovery of a ZLinx ZP24D Radio Modem

The ZP24D-25RM is  a 2.4 Ghz radio modem by B&B Electronics, branded as 'Zlinx'. Although sold as Plug&Play, it comes with basic software that actually shows quite a lot of options.
And if you get some settings wrong (like the sleep mode) , it may become impossible to access the modem.
The standard software however does not have a solution for this. There is no way to revert to 'Factory Settings' without connecting to the modem in command mode, which is no longer possible because the settings are wrong. There is no reset button or switch setting to manually reset it, so you are stuck .

When opening the modem in search of a reset-switch, it was found however that the this unit is actually just a standard XBee module with additional interfacing electronics.

The XBee is a XBEE PRO S1, a fairly common module, which makes searching for a solution a little easier.

The following comes from the Digi website, ( http://knowledge.digi.com/articles/Knowledge_Base_Article/Recovery-procedure-for-XBees/?q=xbee+reset&l=en_US&fs=Search&pn=1 ) and disciusses ways to recover a 'sleeping Xbee:

A note regarding sleeping XBees:
If sleep mode has been enabled, the XBee may appear to be unresponsive since X-CTU expects the radio to be awake when performing any action on the radio. To see if the module is sleeping, go to the terminal tab and watch the Line Status indicator. If CTS periodically flashes, then the module is sleeping and only momentarily waking up.

Now this is exactly what has happened to my Zlinx. And they offer a solution, which almost works, except for a few issues.

First we will need the 'X-CTU' software, legacy version :
 (This was hard to find on the Digi website, but just Google it and the page will pop up.)

Then, if the X-CTU software connects to the unit, it will not recognize the module since it contains non-standard firmware.
To solve this, go to the folder where the ZLinx software is installed (E.G. C:\Windows\Program Files(x86)\B&B Electronics\ZLinx\ZlinxManager) There you'll find the folder 'Update' with the firmwares for the different types of Zlinx modems. Now copy all these folders to the 'update' folder in the folder where the X-CTU software is installed. (E.G. C:\Program Files (x86)\Digi\XCTU\update).

Now you can start the X-CTU software, select the right COM port and baud rate and then go to the 'Modem Configuration' tab. Select the modem type from the drop-down box:
FIRST click 'Show Defaults', so all settings are factory default. Then click 'Write'. The software will try to connect to the modem, and fail:
Now it's time to reset the XBee by switching power Off and On. The program will continue, and write the default settings to the XBee.

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