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LS 1000 Product Reference Guide: Chapter 4, Programming the LS 1004
Software Handshaking
This parameter offers control of the data transmission process in addition to, or instead
of, that offered by hardware handshaking. These options may be combined; for
example, ACK/NAK with ENQ.
• No software handshaking
• 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 of that message.
• 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 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 a
None
ACK/NAK
coverBook Page 35 Monday, December 1, 1997 2:19 PM