HEIDENHAIN TNC 407 (243 020) Technical Manual User Manual
Page 685
Table of control characters:
Character
Name
Description
SOH
Start of Header
SOH identifies the beginning of the
data transfer header. This is a
character string that contains the
program number and information
about the type of program and the
transfer mode.
STX
Start of Text
STX identifies the beginning of a
program block.
ETB
End of Text Block
ETB terminates a data transfer block.
The character that follows ETB (BCC)
is used for data checking.
DC1
Start data transfer (XON)
DC1 starts the transfer of data.
DC3
Stop data transfer (XOFF)
DC3 stops the transfer of data.
ETX
End of Text
ETX is transmitted at the end of a
program.
EOT
End of Transmission
EOT terminates the data transfer and
establishes the idle state. The
character is transmitted by the TNC
at the end of a program input and to
the external device in the event of an
error.
ACK
Positive checkback
(Acknowledge)
ACK is transmitted by the receiver
when a data block has transferred
without error.
NAK
Negative checkback (Not
Acknowledge)
NAK is transmitted by the receiver
when a data block has transferred
with an error. The transmitter must
re-transmit the block.