Check Receive Errors; Hardware Handshaking - Symbol LS4278 Product Reference Manual

7-12 LS4278 Product Reference Guide

Check Receive Errors

Select whether or not the parity, framing, and overrun of received characters are checked. The parity value of received characters is
verified against the parity parameter selected above.
*
Check For Received Errors

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 asserted, the scanner waits up to Host Serial Response Time-out for the
host to de-assert the CTS line. If, after Host Serial Response Time-out, 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 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, the CTS line is
not 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 negating 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 communication 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 jumpered to the active state.
• None: Scan the bar code below if no Hardware Handshaking is desired.
• Standard RTS/CTS: Scan the bar code below to select Standard RTS/CTS Hardware Handshaking.
(Enable)
Do Not Check For Received Errors
(Disable)