Chapter-5
Interface
NLV-5201 User's Manual
50
1st
A) No Handshaking
The scanner communicates regardless of the state of the host system.
* In this setting, the commands from the host system may not be received correctly.
B) BUSY/READY
The scanner and the host system notify each other when they are ready to receive data
(BUSY/READY) via their RTS line. When they are connected as shown in the figure below, the CTS
line can be used to check if the other side is busy (off) or ready to receive data (on).
The scanner
’s RTS is normally on (so ready to receive data) except during the processing of received
data, while transmitting data, and while it is busy processing 1D/2D menu codes. When the scanner
wants to send data, it first will check if its CTS line is on (to be sure that the host is ready to receive
data). If the CTS line is off, the scanner does not send the data but waits for a specific timeout period
for the CTS line to be tuned on. If the CTS line is not turned on within the time specified, the data
transmission will be aborted.
Scanner
Host System
TxD
TxD
RxD
RxD
Scanner
Host System
TxD
TxD
RxD
RxD
RTS
RTS
CTS
CTS
TxD
CTS
RTS
Cannot Receive Command
Scanner
Host System
CTS
RTS
RxD
Decode
Finish
Wait to
Send
Send
Wait to
Send
Send
Software
Buzzer