Symbol LS 3408 Product Reference Manual page 108

6-18 LS 3408 Product Reference Guide
Software Handshaking (continued)
ENQ
When this option is selected, the 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 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.
XON/XOFF
An XOFF character turns the scanner transmission off until the scanner receives an XON character.
There are two situations for XON/XOFF:
• XOFF is received before the scanner has data to send. When the scanner 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 scanner 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 scanner receives an XON character, it sends the rest of the data
message. The scanner waits up to 30 seconds for the XON.
ENQ
ACK/NAK with ENQ
XON/XOFF