Data Bits; Hardware Handshaking - Symbol DS 3478 Product Reference Manual

Data Bits

This parameter allows the digital scanner to interface with devices requiring a 7-bit or 8-bit ASCII protocol.

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 digital scanner reads the CTS line for activity. If CTS is asserted, the digital scanner waits up to the Host Serial Response
Time-out for the host to de-assert the CTS line. If the CTS line is still asserted after the Host Serial Response Time-out
expires (default), 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 the Host Serial Response Time-
out for the host to assert CTS. When the host asserts CTS, the digital scanner transmits data. If the CTS line is still de-
asserted after Host Serial Response Time-out expires (default), the digital scanner sounds a transmission error and discards
the data.
• When data transmission is complete, the digital scanner de-asserts RTS 10 msec after sending the last character.
• The host responds by de-asserting CTS. The digital scanner checks for a de-asserted CTS upon the next data transmission.
During data transmission, the CTS line should be asserted. If CTS is de-asserted for more than 50 ms between characters, the digital
scanner aborts transmission, sounds a transmission error, and discards the data.
If this communications sequence fails, the digital scanner issues an error indication and discards the data. Rescan the data.
If hardware handshaking and software handshaking are both enabled, hardware handshaking takes precedence.
The DTR signal is jumpered (set) to the active state.
7-Bit
RS-232 Interface 7-13
*
8-Bit