HEIDENHAIN TNC 306 Technical Manual - Manual (Page 424)

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TNC 406/TNC 306 2 TNC data interfaces 8-11
2.2.2 Signal levels
The RS-232-C interface must differentiate between two different signal lines and their levels.
Data lines:
The data signals are defined as being logic "1" (MARK) over the range –3V to –15V and as logical "0"
(SPACE) over the range +3V to +15V.
Control and signal lines:
These signals are defined as being ON (High) over the range +3V to +15V and as OFF (Low) over the
range from –3V to –15V.
For all of the signals, the voltage range from –3V to +3V is not defined as a logic level and can
therefore not be evaluated.
– 1 3
U [V]
+ 15
– 15
+ 1 3
Datensignale
Data signals
Steuer- und Meldesignal
Control and message signal
"0"
SPACE
HIGH
ON
"1"
MARK
LOW
OFF
0
2.2.3 Signal designation
The RS-232-C interface distinguishes between data lines, control/signal lines and the earth
conductor.
Data lines:
TxD Transmitted data
RxD Received data