ZebraLink SDK intermittent connectivity or connection freezes

Article ID: 37493795

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Topic or Information

 This solution is useful for:

  • Users experiencing intermittent connectivity with the ZebraLink SDK
  • Users experiencing freezing after specific function calls 

 

Applies To

ZebraLink SDK
Zebra Mobile Printers Except ZQ110, EM Series

Excludes: 2824 Series, 2844 Series, S4M (E53 Firmware Version), 888 DD/TT Series, MZ Series, ZQ110, EM220, EM220II, All Kiosk (except KR403)

Details

The ZebraLink SDK for mobile devices (Android, Blackberry, iOS, Windows CE/Mobile) may demonstrate semi-consistent freezes or intermittent connectivity during the execution of an application.  This behavior may or may not be directly related to specific and repeatable conditions, therefore potentially appearing at random intervals.  While this solution is not all encompassing, it provides users with known issues that have caused these symptoms before.  Check for the following if you are experiencing the symptoms:

  • Use of ZebraPrinterFactory's method getInstance: This method can cause an unknown language exception to be thrown especially with older printer firmware and older SDK versions.  Try to avoid using this method if possible.  As a workaround, create a ZebraPrinter object directly instead of calling this getInstance
     
  • Use of the graphic utility's printImage method that calls a bitmap object as a parameter:  This method has caused applications to freeze in very specific conditions.  It is encouraged to use the alternative printImage method that passes a file path as a parameter.  See the SDK documentation for specific details on implementing this alternate method. 
     
  • Successive and immediate calls to similar methods can cause the SDK to stop responding:  It is generally encouraged to leave ample time in between function calls that initiate communication with the printer.  For example - repeated calls to open and close a connection to a printer should be padded with a three to four second wait time in between. 
     
  • Radio frequency interference: while not common, it is possible that nearby equipment using radio signals at similar frequencies could be interfering with the device in question.  If it is possible that surrounding equipment could be interfering with the device, try to run the setup in an area without the radio traffic.