HEIDENHAIN TNC 306 Technical Manual - Manual (Page 441)

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TNC 406/TNC 306 3 Standard data transmission protocol 3/97
3 Standard data transmission protocol
3.1 General
This protocol can be set in operating mode EXT via the machine parameters.
In the following, the control characters which are sent and received with this protocol are listed for
the various transmission alternatives. When outputting a file, the character is sent 50 times
at the start of the file. When reading in, however, the control ignores this character. Therefore it
does not matter how often the peripheral device sends the character before the file.
In this protocol, if an error is to be signaled to the TNC, the following sequence of instructions must
be sent:
<1> 'ERROR NUMBER'
Listed below are the transmission protocols for the various alternatives for data output and input.
EXT mode is set:
– Control character for "End of Text" -
– Control character for "End of Transmission" -
– Software handshake
3.1.1 Calling the program directory
Using the menu item "Program Directory", the list of file names can be requested from an external
memory and displayed in the TNC.
If the external directory is requested, the TNC sends control character .
If the request is immediately interrupted with the END key, the TNC sends characters
and no directory is read in.
If the request is not interrupted, the peripheral unit sends all of the external programs in order. Their
names are then shown in the TNC.