Symbol LS 3408, Product Reference Manual

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LS 3408 Product Reference Guide 6-14
Hardware Handshaking
The data interface consists of an RS-232 port 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 not selected, scan data is transmitted as it becomes available.
If Standard RTS/CTS handshaking is selected, scan data is transmitted according to the following
sequence:
• The scanner reads the CTS line for activity. If CTS is de-asserted, the scanner waits up to
the Host Serial Response Time-out for the host to de-assert the CTS line. If, after Host Serial
Response Time-out (default), the CTS line is still asserted, the scanner sounds a transmit
error, and any scanned data is lost.
• When the CTS line is de-asserted, the scanner asserts the RTS line and waits up to the Host
Serial Response Time-out for the host to assert CTS. When the host asserts CTS, data is
transmitted. If, after Host Serial Response Time-out (default), the CTS line is still de-
asserted, the scanner sounds a transmit error, and discards the data.
• When data transmission is complete, the scanner de-asserts RTS 10 msec after sending the
last character.
• The host should respond by de-asserting CTS. The scanner checks for a de-asserted CTS
upon the next transmission of data.
During the transmission of data, the CTS line should be asserted. If CTS is de-asserted 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.
The DTR signal is jumped to the active state.