Hardware Handshaking - Symbol LS 6000 Series Product Reference Manual

Hardware Handshaking

The data interface consists of an RS-232C port. The port has
been designed to operate either with or without the hardware
handshaking lines, Request to Send (RTS), and Clear to Send
(CTS).
If Standard RTS/CTS handshaking is selected, scan data is
transmitted according to the following sequence:
!
The controller reads the CTS line for activity. If CTS is
asserted, the controller waits up to 2 seconds for the host
to negate the CTS line. If, after 2 seconds (default), the
CTS line is still asserted, the scanner sounds a transmit
error and any scanned data is lost.
!
When the CTS line is negated, the controller asserts the
RTS line and waits up to 2 seconds for the host to assert
CTS. When the host asserts CTS, data is transmitted. If,
after 2 seconds (default), the CTS line is not asserted, the
scanner sounds a transmit error and discards the data.
!
When data transmission is complete, the controller
negates RTS 10 msec after sending the last character.
!
The host should respond by negating CTS. The
controller 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 deasserted for more than 50 ms between
characters, the transmission is aborted, the scanner sounds a
transmission error, and the data is discarded.
If the above communications sequence fails, the scanner issues
an error indication. In this case, the data is lost and must be
rescanned.
Programming the LS 6000
5-103