HEIDENHAIN MANUALplus 620 Technical Manual page 1783

9.7 Data Transmission Protocols
9.7.1 Standard communications protocol
General
information
January 2012
To set the standard communications protocol:
 See "MP_protocol" on page 1775.
When outputting a file, the <NUL> character is sent exactly 50 times at the
start of file. When reading in, however, the control unit ignores this character,
regardless of how often the peripheral sends the <NUL> character before the
file.
The program blocks are not checked for correctness but are transmitted one
after the other.
If you wish to signal an error to the control in the standard communications
protocol, you must send the following sequence of instructions:
<ESC><1><Error number>
If the receiver's data buffer is full, the transmission can be stopped and
resumed in one of two ways:
Software handshaking
• Stop transfer by sending the character <DC3> (XOFF)
• Continue by transmitting the character <DC1> (XON)
Hardware handshaking
• By suitable levels on the control and signal lines RTS and CTS of
interfaces RS-232-C/V.24 or RS-422/V.11
Twelve characters before the receiving buffer is full, the control transmits the
character <DC3> to the transmitter in order to terminate transmission.
Example: Protocol for conversational NC program
<NUL><NUL><NUL><NUL> 50 times
0 BEGIN PGM 1 MM<CR><LF> 1st program block
1 TOOL DEF 1 L+0 R+3<CR><LF> 2nd program block
26 END PGM 1 MM <CR><LF> End of program
... ...
<ETX><EOT> Close the data transmission menu
Example of software handshake
Control to peripheral device
12 Z + 2 FMAX<CR><LF>
13 Z -10 F100 M03<CR><LF>
9.7 Data Transmission Protocols
Peripheral device to control
Receiving buffer full: <DC3>
Receiving buffer ready again: <DC1>
...
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