Intermec EasyCoder 7421 User Manual page 77

XON/XOFF protocol uses the ASCII characters <DC1> (XON)
and <DC3> (XOFF) to start and stop the flow of data from the
host to the printer. The printer does not restrict the message
length for XON/XOFF protocol. That is, the printer processes
information as it is being downloaded and stops when there is
no more information.
<STX> and <ETX> are optional characters. However, if you send
an STX, the printer ignores all other characters until you send an
ETX.
Intermec provides two versions of the XON/XOFF protocol. The
Intermec version of XON/XOFF has the printer respond to each
message with its current status. The other version conforms to
generally accepted industry standards that include no end-of-
message response being sent to the host other than XOFF. In
addition, a DC3 is sent to the host if the printer is offline or if
media fault occurs. An XON is sent on power up.
Since the printer uses DC1 and DC3 for data flow control, the
printer status characters are different from those of the Standard
Protocol.
Buffer already full
Ribbon fault
No label stock
Printhead hot
Buffer now full
Label at strip pin
Label skipping
Printing
Ready
If the host ignores the printer sending an XOFF, the printer
resends an XOFF after receiving every 15 characters from the
host. In the case of transmission error, the printer discards the
characters with the error and keeps the rest of the message block.
GS
US
EM
SI
DC4
FS
DC2
DC2
DC2