HEIDENHAIN TNC 430 PA/M - Configuration of Interfaces; Control Characters

8 – 14 HEIDENHAIN Technical Manual TNC 426, TNC 430
8.3 Configuration of Interfaces
8.3.1 Control Characters
Overview of control characters specific to HEIDENHAIN
Character Designation Description
SOH Start of Header Identifies the beginning of the data
transfer header. The character string
contains the program number and
information about the type of
program and the transfer mode.
STX Start of Text Identifies the beginning of a program
block.
ETB End of Text Block Terminates a data transfer block.
The character that follows (BCC) is
used for data checking.
DC1 XON Starts the transfer of data.
DC3 XOFF Stops the transfer of data.
ETX End of Text Transmitted at the end of a program.
EOT End of Transmission Terminates the data transfer and
establishes the idle state. This
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 Acknowledgment Transmitted by the receiver when a
data block has transferred without
error.
NAK Negative
Acknowledgment
Transmitted by the receiver when a
data block has transferred with an
error. The transmitter must re-
transmit the data block.