Motorola MS4404 사용자 설명서
9 - 12 Symbol MS4404/MS4407 Integration Guide
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.
handshaking. There are five options.
If Software Handshaking and Hardware Handshaking are both enabled, Hardware Handshaking takes
precedence.
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 imager expects either an ACK or NAK
response from the host. When a NAK is received, the imager 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 imager
issues an error indication and discards the data.
response from the host. When a NAK is received, the imager 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 imager
issues an error indication and discards the data.
The imager waits up to the programmable Host Serial Response Time-out to receive an ACK or NAK. If the
imager 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.
imager 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 imager 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 imager 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.
data. If an ENQ is not received within the Host Serial Response Time-out, the imager 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.
from the host, an additional ENQ is not required.
•
XON/XOFF: An XOFF character turns the imager transmission off until the imager receives an XON
character. There are two situations for XON/XOFF:
character. There are two situations for XON/XOFF:
•
XOFF is received before the imager has data to send. When the imager has data to send, it waits up to
Host Serial Response Time-out for an XON character before transmission. If the XON is not received
within this time, the imager issues an error indication and discards the data.
Host Serial Response Time-out for an XON character before transmission. If the XON is not received
within this time, the imager issues an error indication and discards the data.
•
XOFF is received during a transmission. Data transmission then stops after sending the current byte.
When the imager receives an XON character, it sends the rest of the data message. The imager waits
indefinitely for the XON.
When the imager receives an XON character, it sends the rest of the data message. The imager waits
indefinitely for the XON.