HEIDENHAIN TNC 306 Technical Manual - Manual (Page 423)

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TNC 406/TNC 306 2 TNC data interfaces 3/97
2 TNC data interfaces
2.1 General
The TNC 306 has a data interface, the RS-232-C. The HEIDENHAIN FE 401 floppy disk unit, ME 101
magnetic tape unit and external devices with appropriate data interfaces (computers, printers,
readers, punches) can be connected via the RS-232-C interface.
Two transmission protocols are available for data transfer:
– Standard data transmission protocol (ME 101 and non-HEIDENHAIN devices)
– Data transfer with Block Check Character (FE 401 and PC with HEIDENHAIN data transfer
software)
2.2 RS-232-C/V.24 interface
RS-232-C is the designation of a serial interface based on the EIA standard of the same name and
can handle transmission rates up to 19 200 baud. Data transfer is executed asynchronously, with a
start bit before each character and one or two stop bits after each character. The interface is
designed for transmission distances of up to 20 metros.
The RS-232-C interface has been adopted with slight modifications and introduced into Europe as
the V.24 interface. The relevant German standard is DIN 66020.
2.2.1 Hardware
The physical connection between two RS-232-C interfaces is an asymmetrical line, i.e. the common
ground connection between transmitter and receiver is used as a return line.
Physical connections:
Sender
Transmitter
Übertragungsstrecke
Transmission path
Empfänger
Receiver
RxD TxD
RxD TxD