HEIDENHAIN TNC 306 Technical Manual - Manual (Page 432)

3/97
TNC 406/TNC 306 2 TNC data interfaces 8-19
Table of control characters:
Character Meaning Description
SOH Start of Header Indicates start of transfer of the data
header. The header is a sequence of
characters containing the program
number and information concerning
the type of program and
transmission mode.
STX Start of Text Indicates start of program block.
ETB End of Transmission Block ETB ends a data transfer block. The
character following ETB is used for
data checking (BCC).
DC1 Start data transfer (XON) DC1 starts data transfer after a stop.
DC3 Stop data transfer (XOFF) DC3 stops data transfer.
ETX End of Text ETX is sent at the end of the
program.
EOT End of Transmission EOT ends data transmission and
produces the quiescent state. This
character is sent by the TNC at the
end of program input, and as an error
to external devices
ACK ACKnowledged ACK is sent by receiver when a data
block has transferred without error.
NAK Not AcKnowledged NAK is sent by the receiver when a
data block has transferred incor-
rectly. The transmitter must then
transmit the data block again.