Hi there,

I have a customer with a large number of RW420 printers.  We have a requirement to print to these printers on Android via classic Bluetooth.  Printing is via our custom Android app using standard Android Java APIs / SDKs and RFCOMM sockets.

An issue has been reported where intermittently an additional carriage return / line feed is inserted into the printed output.  This isn't part of the data that is sent from our application.  We've seen this in our product support teams when sending a 2k text buffer to the printer.  Periodically a crlf appears and this is not in the buffer we have sent.  Repeating the same 2k buffer doesn't repeat the crlf in the same place but may repeat in another point in the output.  This may happen when there's a delay or pause in sending data via Bluetooth.  This problem has also been seen when running the RW420 printer in diagnostic mode, which is how we managed to confirm that the crlf characters were not in the buffer that we send.  This has not been seen in other Zebra printers, although we only have access to a small number such as the ZQ510.  We have tried on a number of Android phones and tablets with different Android OS versions, ranging from 10 through to 14, and all replicated the same issue.

Any thoughts on what may be going on here?  Would there be a reason why the RW420 printer would insert a crlf?  Are there any configuration options that may help here?  As mentioned we have had no issues with the ZQ510 and I presume the ZQ520 would also be fine.

Thanks!