Software Handshaking - Symbol DS6707 Product Reference Manual

Hardware Handshaking (continued)
RTS/CTS Option 3

Software Handshaking

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: When this option is selected, data is transmitted immediately. No response is expected from host.
•
ACK/NAK: When this option is selected, after transmitting data, the digital imager scanner expects either an
ACK or NAK response from the host. When a NAK is received, the digital imager scanner transmits the same
data again and waits for either an ACK or NAK. After three unsuccessful attempts to send data when NAKs
are received, 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: When this option is selected, the digital imager scanner waits for an ENQ character from the host
before transmitting data. If an ENQ is not received 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.
RS-232 Interface 8 - 13
RTS/CTS Option 2