Metrologic Instruments IS1000 ユーザーズマニュアル

 

 
 
 
 
 
 

10

Once this protocol is activated, the decoder waits for an acknowledgment from the 
host system: 

•  ACK  (06 hexa) means:  message correctly received by the host system. 

• NAK  (15 hexa) means: message incorrectly received by the host, upon 

reception of this character the decoder resends the 
message. 

 

 

 

 

Using this protocol, the host system can control the data flow coming from the 
decoder: 

•  XON  (11 hexa) means:  host system ready to receive data. 

•  XOFF  (13 hexa) means:  host system busy, the decoder stops the transmission 

and waits for an XON. 

 

 

 

 

This protocol is a hardware "handshake" between the decoder and the host 
system. Before transmitting data, the decoder rises its RTS signal (pin 4) to +10 
volt and waits for a +10 volt signal on its CTS (pin 5) from the host. The rest 
position of the two pins is -10 volt.