Motorola DS6707 ユーザーズマニュアル

RS-232 Interface 8 - 13

This parameter offers control of the data transmission process in addition to, or instead of, that offered by hardware 
handshaking. There are five options.

If software handshaking and hardware handshaking are both enabled, hardware handshaking takes precedence.

None: Select this option to transmit data immediately. No response is expected from host.

ACK/NAK: If you select this option, after transmitting data, the digital imager scanner expects either an ACK 
or NAK response from the host. When it receives a NAK, the digital imager scanner transmits the same data 
again and waits for either an ACK or NAK. After three unsuccessful attempts to send data after receiving 
NAKs, the digital imager scanner issues an error indication and discards the data.

The digital imager scanner waits up to the programmable Host Serial Response Time-out to receive an ACK 
or NAK. If the digital imager scanner does not get a response in this time, it issues an error indication and 
discards the data. There are no retries when a time-out occurs.

ENQ: If you select this option, the digital imager scanner waits for an ENQ character from the host before 
transmitting data. If it does not receive an ENQ within the Host Serial Response Time-out, the digital imager 
scanner issues an error indication and discards the data. The host must transmit an ENQ character at least 
every Host Serial Response Time-out to prevent transmission errors.

ACK/NAK with ENQ: This combines the two previous options. For re-transmissions of data, due to a NAK 
from the host, an additional ENQ is not required.