INDICATORS 
 
Visual 
 
Figure 29.  LED Configuration 
 
The MS9540 has three LED indicators located on the head of the scanner.   
The MS9520 has two LED indicators located on the head of the scanner.   
When the scanner is in operation, the flashing, or stationary activity of the LEDs 
indicates the status of the scanner and the current scan.  
 
All LEDs are Off 
The LEDs will not be illuminated if the scanner is not receiving power from the 
host or transformer. 
 
The scanner is in stand-by mode, and CodeGate is enabled.  Present a bar 
code to the scanner and the green LED will turn on when the laser turns on. 
 
 
Steady Yellow (MS9540’s Only) 
The CodeGate button is not active.  If a bar code is in the scan field, the laser 
will turn on.  The bar code will be decoded and transmitted to the host 
automatically. 
 
 
Steady Green 
When the laser is active, the green LED is illuminated.  The green* LED will 
remain illuminated until the laser is deactivated (default mode only). 
 
 
Steady Green and Single Red Flash 
When the scanner successfully reads a bar code, the red* LED will flash and 
the scanner will beep once.  If the red LED does not flash or the scanner does 
not beep once, then the bar code has not been successfully read (default mode 
only). 
 
  After a successful scan, the scanner transmits the data to the host 
device.  Some communication modes require that the host inform the 
scanner when data is ready to be received.  If the host is not ready to 
accept the information, the scanner’s red LED will remain on until the 
data can be transmitted.  
 
*  In some custom units the standard green LED has been replaced with a blue LED and 
the red LED has been replaced with a white LED.