Symbol LS 6800, User Manual

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LS 6800 Product Reference Guide
Hardware Handshaking
The LS 6800 scanner uses an RS-232C data interface. The RS-232C port is designed to
operate either with or without the hardware handshaking lines
RTS , Request to Send , and
CTS , Clear to Send .
If RTS / CTS handshaking is selected, scan data is transmitted according to the following
sequence:
t
The scanner reads the CTS line for activity. If CTS is asserted, the scanner waits up
to one second for the host to negate the CTS line. After two seconds, if the CTS line
is still asserted, the scanner sounds a transmit error and any scanned data is lost.
t
When the CTS line is negated, the scanner asserts the RTS line and waits for two
seconds for the host to assert CTS. When the host asserts CTS, data is transmitted.
If the CTS line is not asserted after two seconds, the scanner sounds a transmission
error and discards the data.
t
When data transmission is complete, the scanner negates RTS 10 msec after sending
the last character.
t
The host should respond by negating CTS. The scanner checks for a negated CTS
upon the next transmission of data.
During the transmission of data, the CTS line should be asserted. If CTS is asserted for less
than 50 ms between characters, the transmission is aborted. The scanner sends a transmit
error, and the data is discarded.
t
If the above communications sequence fails, the scanner issues an error beep. Data
is lost and must be rescanned.
Note: The DTR signal is jumpered active.