Hardware Handshaking - Motorola Symbol DS3407 Reference Manual

7 - 12 Symbol DS3407 Product Reference Guide

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).
Disable Standard RTS/CTS handshaking to transmit scan data as it becomes available. Select Standard RTS/CTS
handshaking to transmit scan data according to the following sequence:
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The digital scanner reads the CTS line for activity. If CTS is asserted, the digital 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
(default), the CTS line is still asserted, the digital scanner sounds a transmit error and discards any scanned
data.
•
When the CTS line is de-asserted, the digital 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, the digital scanner transmits
data. If, after Host Serial Response Time-out (default), the CTS line is not asserted, the scanner sounds a
transmit error and discards the data.
•
When data transmission completes, the digital scanner de-asserts RTS 10 msec after sending the last
character.
•
The host should respond by negating CTS. The digital 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 deasserted for more than 50 ms
between characters, the digital scanner aborts transmission, sounds a transmission error, and discards the data.
If this communication sequence fails, the digital 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 to the active state.
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None: Scan this bar code to disable hardware handshaking.
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Standard RTS/CTS: Scan this bar code to select Standard RTS/CTS hardware handshaking.
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RTS/CTS Option 1: If you select RTS/CTS Option 1, the digital scanner asserts RTS before transmitting and
ignores the state of CTS. The digital scanner de-asserts RTS when transmission completes.
•
RTS/CTS Option 2: If you select Option 2, RTS is always high or low (user-programmed logic level).
However, the digital scanner waits for CTS to be asserted before transmitting data. If CTS is not asserted
within Host Serial Response Time-out (default), the digital scanner issues an error indication and discards
the data.
•
RTS/CTS Option 3: If you select Option 3, the digital scanner asserts RTS prior to any data transmission,
regardless of the state of CTS. The digital scanner waits up to Host Serial Response Time-out (default) for
CTS to be asserted. If CTS is not asserted during this time, the digital scanner issues an error indication and
discards the data. The digital scanner de-asserts RTS when transmission completes.