Figure 14: Busy/Ready; Figure 15: Rts/Cts Data Transmission; Figure 16: Cts, Txd Signal Timing - Opticon MDI-4000 Series Serial Interface Manual

BUSY/READY
The scan engine and the host system notify each other when they are ready to receive data
(BUSY/READY) through their RTS line. When they are connected (as shown in the next
diagram), the CTS line can be used to check if the other side is busy (off) or ready to receive
data (on).
TxD
RxD
Scan Engine
RTS
CTS

Figure 14: BUSY/READY

The scan engine's RTS line is normally on (ready to receive data) except when processing
received data, transmitting data, and processing 1D or 2D menu barcodes. When the scan
engine wants to send data, it makes sure that the host is ready to receive data by seeing if its
CTS line is on. If the CTS line is off, the scan engine does not send the data and waits for a
specific timeout period for the CTS line to be turned on. If the CTS line is not turned on within
the specified time, the data transmission is canceled.
Scan Engine
RTS
CTS
TxD
Decode Wait to
Finish

Figure 15: RTS/CTS Data Transmission

4.1.6.2 CTS, TxD Signal Timing
When the CTS line is pulled low during a transmission, the transmission stops. When the CTS
line is pulled high again, the transmission continues.
TxD n-1
CTS

Figure 16: CTS, TxD Signal Timing

Cannot Receive Command
Send Wait to
Send Send
n
MDI-4000 Series Serial Interface Manual
TxD
RxD
Host System
RTS
CTS
Host System
Send Software
Buzzer
n+1 n+2
CTS
RTS
RxD
23