BZ-TECH D-6448 Manual De Instrucciones página 204

Programming Guide S-100W - Ver. 1.0
Hardware Handshaking
The data interface consists of a serial 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 decoder reads the CTS line for activity. If CTS is asserted, the decoder 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 decoder sounds a transmit error, and any
scanned data is lost.
• When the CTS line is de-asserted, the decoder 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 (default), the CTS line is not asserted, the
decoder sounds a transmit error, and discards the data.
• When data transmission is complete, the decoder de-asserts RTS 10 msec after sending the
last character.
• The host should respond by negating CTS. The decoder 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 transmission is aborted, the decoder sounds a
transmission error, and the data is discarded. If the above communication sequence fails,
the decoder 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.
• 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.
• RTS/CTS Option 1: When RTS/CTS Option 1 is selected, the decoder asserts RTS before transmitting
and ignores the state of CTS. The decoder de-asserts RTS when the transmission is complete.
• RTS/CTS Option 2: When Option 2 is selected, RTS is always high or low (user-programmed logic level).
However, the decoder waits for CTS to be asserted before transmitting data. If CTS is not asserted within
Host Serial Response Time-out (default), the decoder issues an error indication and discards the data.
• RTS/CTS Option 3: When Option 3 is selected, the decoder asserts RTS prior to any data transmission,
regardless of the state of CTS. The decoder waits up to Host Serial Response Time-out (default) for CTS
to be asserted. If CTS is not asserted during this time, the decoder issues an error indication and discards
the data. The decoder de-asserts RTS when transmission is complete.
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