User Guide User Manual

Interfaces User guide
174
ENQ/STX protocol In addition to this XON/XOFF message, the possibility exists of re-
questing a status byte from the printer using the ENQ code (hex. 05,
dec. 5). The STX code (hex 02, dec. 2) is used to clear any error
messages (parity error, buffer overflow).
STX (hex02) Clears any previous parity or framing error as well
as any buffer overflow error.
ENQ (hex05) The current printer status is sent to the host.
XON/XOFF This protocol is automatically used for data flow
control and printer status handling.
HandThr.=ON The STX and ENQ characters are not filtered out
of the data stream and control the interface in ad-
dition.
HandThr.=OFF The STX and ENQ are filtered out of the data
stream and handled immediately by the interface.
ETX/ACK protocol ETX (hex03) Block end character
ACK (hex06) Acknowledgement informing the host that further
data may be transmitted.
XON/XOFF This protocol is used in addition to data flow con-
trol and printer status handling.
HandThr.=ON An ETX is not acknowledged by ACK before all
previously arrived data have been printed.
HandThr.=OFF When the printer receives an ETX, it returns an
ACK to the host. Any previously sent data or
blocks may still be present in the printer buffer.
Status byte Bit 0 – 1 BUSY
Bit 1 – 1 Off Line
Bit 2 – 0 Paper end
Bit 3 – 1 Always 1
Bit 4 – 1 Cover open
Bit 5 – 1 Buffer overflow
Bit 6 – 1 Parity or frame error
Bit 7 – 0 Always 0