Symbol LT 1804, Product Reference Manual

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LT 1804 Product Reference Guide: Programming the LT 1804
2. ACK/NAK Only
The ACK/NAK option checks the success or failure of transmission. The
scanner expects one of the following host responses after a data
transmission:
<ACK> - Acknowledges a valid and successful transmission.
<NAK> - Indicates a problem with the transmission.
Whenever a <NAK> is received, the unit retransmits the same data and
awaits an ACK/NAK response. After three unsuccessful attempts to
transmit the same data, the scanner aborts any further communication
attempts on that message. Transmission error is indicated by the unit
sounding 4 long beeps.
3. ENQ ONLY
The ENQ option needs the host to request data before it is transmitted to
the host. This ensures that data transmission occurs only when the host is
ready to receive.
When you select the wait for ENQ option, the scanner waits for an ENQ,
Enquire, character from the host before it transmits data; otherwise, the
unit transmits data without waiting for an ENQ character from the host.
With ENQ enabled, the scanner must receive an ENQ from the host within
a 2 second period after the last activity or 4 long beeps are sounded to
indicate a transmission error; the unit is now ready to scan again.
4. ACK/NAK with ENQ
This combines both handshaking options.
RTS Line State
This parameter is used to set the idle state of the Serial Host RTS line.
Host Serial Response Time-out
This parameter specifies how long the scanner waits for an ACK, NAK, or CTS
before determining that a transmission error has occurred. This only applies
when an ACK/NAK Software Handshaking mode or RTS/CTS Hardware
Handshaking option is enabled. The delay period can range from 0.5 to 9.9
seconds in .1-second increments.