13
3-5 RS-232 interface
XON: 0x11
XOFF: 0x13
ACK: 0x06
NAK: 0x15
Flow control:
None
- The communication only uses TXD and RXD signals without any hardware or software
handshaking protocol.
RTS/CTS
– If the 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 scanner will issue an error indication.
Two-direction flow control -
The 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 scanner
’s transmission off unit the scanner receives
an <XON> character.
ACK/NAK
–
After transmitting data, the scanner expects either an <ACK> character (acknowledge)
or <NAK> character response from the host. When a <NAK> character is received, the 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 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 scanner when it waits for a
handshaking acknowledgment form the host.
