Motorola LS4208 用户手册

6 - 10 Symbol LS4208 Product Reference Guide

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.

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.