HEIDENHAIN TNC 407 (243 020) Technical Manual - Manual (Page 668)

01.98
TNC 407/TNC 415/TNC 425 2 TNC data interfaces 8-21
2.5 Configuration of interfaces
2.5.1 Selection of interfaces
Either data interface may be inhibited with MP 5000.
MP 5000 Inhibit data interfaces
Input range: 0 to 2
0 = no interface inhibited
1 = interface RS-232-C/V.24 inhibited
2 = interface RS-422/V.11 inhibited
If neither of the two interfaces is inhibited, the following settings can be selected with the
appropriate data format and the data transmission protocol.
In addition to the three freely configurable operating modes EXT1/EXT2/EXT3 (for PLC only, see
Section 5 "Data transfer by PLC"), there are three fixed modes (ME, FE1/FE2). The FE1 and FE2
modes have to be set if the HEIDENHAIN floppy disk unit or an external computer using the
TNC.EXE transmission software is connected. In both these modes, the transmission protocol with
Block Check Character is rigidly defined [for the difference between FE1 and FE2 operation: see
Section 4 "Data transfer with block Check Character (BCC)"].
The ME operating mode matches the HEIDENHAIN ME 101 magnetic tape unit and must be
selected if this is to be connected.
In this mode, the standard transmission protocol is set.
However, there is one important difference:
The character is never sent because this character cannot be processed by the magnetic
tape unit.
2.5.2 Freely configurable interfaces
The three operating modes EXT1/EXT2/EXT3 (PLC) are freely configurable via the machine
parameters.
The data format and the type of handshake are set in the MP 5020.
Data bits
Bit 0 can be set to determine whether transmission is to be with 7 or 8 data bits. Transmission with
7 bits is normally used, but 8 bits are needed, especially for printer interfacing.
BCC
If calculation of the BCC produces a number less than $20 (i.e. a control character) then a "Space"
character ($20) is sent in addition immediately before . The BCC will consequently always be
greater than $20 and cannot therefore be recognised as a control character.