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LS 3070 Product Reference Guide: Programming
Software Handshaking
This parameter offers control of the data transmission process. It may be used
instead of, but not in conjunction with, hardware handshaking. The base
station also provides four software handshaking options: NONE, ENQ, ACK/
NAK, and ACK/NAK with ENQ. These options may be combined, for
example ACK/NAK with ENQ. Refer to the chart following the parameter
description.
No Software Handshaking
ACK/NAK Only
The ACK/NAK option checks the success or failure of transmission. The base
station 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 base aborts any further communication attempts on that
message. Transmission error is indicated by the unit sounding 4 short beeps.
When no response for the duration of the serial response time-out parameter
(default 2 seconds), or a NAK is received, the base station will retransmit the
data until an ACK is received, or the third transmit failure. After three
unsuccessful transmission attempts, the unit will abort any further
communication attempts on the current message. It indicates this by sounding
4 long (1 second) beeps.
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.