BZ-TECH D-6448 Manual De Instrucciones página 206

Programming Guide S-100W - Ver. 1.0
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 decoder expects either
an ACK or NAK response from the host. When a NAK is received, the decoder 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 decoder issues an error indication and discards the
data.
• 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 issues an error indication and
discards the data. There are no retries when a time-out occurs.
• ENQ: When this option is selected, the decoder 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 decoder 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.
• XON/XOFF: An XOFF character turns the decoder transmission off until the decoder receives
an XON character. There are two situations for XON/XOFF:
• XOFF is received before the decoder has data to send. When the decoder 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 decoder 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 decoder receives an XON character, it sends the rest of the data
message. The decoder waits indefinitely for the XON.
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