Motorola DS3508, Product Reference Manual

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RS-232 Interface 7 - 11
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:
•
The digital 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 (default),
the CTS line is still asserted, the 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 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.