5-86
LS 400Xi Product Reference Guide
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:
tThe 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.
tWhen 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.
tWhen data transmission is complete, the controller negates RTS 10 msec after
sending the last character.
tThe 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.
If Hardware Handshaking and Software Handshaking are both enabled, Hardware
Handshaking takes precedence.
Note: The DTR signal is jumpered active.