HEIDENHAIN TNC 407 (243 020) Technical Manual - Manual (Page 676)

01.98
TNC 407/TNC 415/TNC 425 2 TNC data interfaces 8-29
The ME transmits this file with all the programs to the control unit. The TNC then selects the
appropriate program and stores it.
A further important difference between EXT1/EXT2/EXT3 mode in the standard
protocol and ME mode is that the character is never sent in ME mode because
the magnetic tape unit is incapable of processing this character.
In this protocol, if an error is to be signalled to the TNC, the following sequence of instructions must
be sent:
<1> 'ERROR NUMBER'
The blocks are not checked for correctness but are transmitted one after the other. If the receiver's
data buffer is full it can stop the transfer and resume in one of two ways:
– Stop transfer by sending the character (XOFF);
continue by transmitting character (XON) (software handshake).
– By suitable levels on the control and message lines RTS and CTS of interfaces
V.24/RS-232-C or V.11/RS-422 (hardware handshake).
Example: Protocol for dialog program
... 50 times
0 BEGIN PGM 1 MM Program block 1
1 TOOL DEF 1 L+0 R+3 Program block 2
.
.
.
26 END PGM 1 MM
End of program
Close data transfer menu