HEIDENHAIN TNC 335 Technical Manual - Manual (Page 522)

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TNC 360 2 TNC data interfaces 8-15
2.3.2 Output to external devices
Any external device, e.g. computers, printers, readers and punches, can be addressed via the
interface. For this purpose, the TNC has a freely configurable interface mode (EXT) which, within
certain limits, permits any setting of the data format and control characters of the required data
transmission protocol.
The setting selected at the external devices must of course match the TNC. On printers, this is done
by setting the DIP-switches or adjusting the transmission parameters.
If data transfer to a computer is desired, appropriate data-transfer software must be installed. To
help in this, HEIDENHAIN offer their TNC.EXE data transfer software, which permits transfer
between TNC and a PC using a fixed transmission protocol.
2.3.3 Reading in and simultaneously executing programs (DNC
operation)
In PROGRAM RUN mode, machine programs can be transmitted with "Block transfer" from an
external memory via the serial data interface and be executed simultaneously (DNC operation). This
allows machine programs which exceed the storage capacity of the control unit to be executed.
After the program has started, executed blocks are erased and further blocks are continuously called
from the external memory.
If the program blocks are read into the TNC faster than they can be executed, the entire NC memory
is initially fully loaded. If it is full, transfer is suspended until a storage space of one NC block is
vacated by execution. Only then is transfer resumed, until once again the memory is filled.
For DNC operation the data transfer protocol must be set with Block Check Character BCC (data
checking).
2.3.4 Communication between TNCs
For certain applications, it is necessary for TNCs to be able to exchange data or to communicate
with each other. This is made possible by the RS-232-C/V.24 interface.
The simplest form of data exchange is the transfer of files (e.g. NC programs) from one TNC to
another. To do this, the same transmission format (ME mode) must be set at both control units and
transfer started. It must be ensured that the receiving control unit is the first to start.
For the application "Positioning module", i.e. further NC axes are required, the positioning values
have to be transmitted from the master logic unit to the slave logic unit. On this basis, data can be
transferred to another TNC via the data interface, using PLC modules at the PLC level (see Section 5
"Data transfer by PLC").
2.4 Data transmission protocols
The TNC enables data and files to be transferred using two different protocols (which can be
selected via the interface setup or the machine parameters).