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3-4 RS-232 interface
Flow control:
None - The communication only uses TXD and RXD signals without any hardware or software
handshaking protocol.
RTS/CTS – If the embedded scanner wants to send the barcode data to the host, it will assert the RTS
signal first, and then waits for the CTS signal from the host to perform normal data communication. If
CTS is not asserted in Response delay, the embedded scanner will issue an error indication.
Two-direction flow control - The embedded scanner asserts the RTS signal when it is OK for the host
to transmit. The host asserts CTS when it is OK for the device to transmit.
XON/XOFF – An <XOFF> character turns the embedded scanner's transmission off unit the embedded
scanner receives an <XON> character.
ACK/NAK – After transmitting data, the embedded scanner expects either an <ACK> character
(acknowledge) or <NAK> character response from the host. When a <NAK> character is received, the
embedded scanner transmits the same data again and waits for either an <ACK> character or <NAK>
character. After three unsuccessful attempts to send data when <NAK> characters are received the
embedded scanner issues an error indication and discards the data.
Inter-character delay: This delay is inserted after each data character transmitted.
Response delay: This delay is used for serial communication of the embedded scanner when it waits for
a handshaking acknowledgment form the host.
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