Motorola MS4404 用户手册

8 - 14 Symbol MS4404/MS4407 Integration Guide

Select whether or not to check the parity of received characters. Use the Parity parameter to select the type of 
parity.

This parameter offers control of the data transmission process in addition to that offered by hardware handshaking. 
Hardware handshaking is always enabled and cannot be disabled by the user.

Disable ACK/NAK Handshaking: When this option is selected, the decoder neither generates nor expects 
ACK/NAK handshaking packets.

Enable ACK/NAK Handshaking: When this option is selected, after transmitting data, the decoder expects 
either an ACK or NAK response from the host. The decoder also ACKs or NAKs messages from the host. 

The decoder waits up to the programmable Host Serial Response Time-out to receive an ACK or NAK. If the 
decoder does not get a response in this time, it resends its data up to two times before discarding the data 
and declaring a transmit error.