Blank labels on Zebra printer using ZPL

Hi,

 

I have a problem with blank labels using ZPL from iOS application to print the label.

We use printer QLn 320 Zebra with firmware V68.19.7Z, non-continuous media with gaps.

 

The printer prints one required label and two blank labels when I use the ZPL command:

 

^XA^MNW

^LH20,20^POI

^FT5,5^FH^A0N,30,30^FDLine1^FS

FT5,45^FH^A0N,30,30^FDLine2^FS

^XZ

 

If I change printer settings and define label length with command:

 

^XA^MNN^LL200^XZ^XA^JUS^XZ

 

and use the following ZPL to print the label

 

^XA

^LH20,20^POI

^FT5,5^FH^A0N,30,30^FDLine1^FS

FT5,45^FH^A0N,30,30^FDLine2^FS

^XZ

 

The printer prints labels with correct size and doesn’t print blank labels.

 

So as I understand the problem with auto detection label size.

 

Could you advice what can be the reason?