There are two reasons for this problem
1）This is dependent on the range and angle of the code.
Please scan at 20-60cm; scan within range for quick and constant decodes; scanning too close or too far away prevents decodes.
Move the scanner closer and further away to find the right working range for the barcodes being scanned.
Hold the device further away for larger symbols.
Move the device closer for symbols with bars that are close together.
Figure 2- 7 Correct position of the scan
2）This is related to the brightness of the ambient light you are scanning
Scanning speed can be affected in very dark rooms or outdoors where there is too much sunlight
If you are in a dark environment, please turn on the scanning head with its own light source to center the barcode for scanning
If you are in a too bright environment, please use your hand or body to partially block the sunlight and center the barcode for scanning