Interfaces
8-13
The following illustration shows the pin assignments for the 9-pin to 25-pin IBM EIA
RS-232C serial cables.
Serial Communication Parameters (RS-232C)
The following paragraphs show acceptable values for serial communication
parameters.
Voltage Level Range
The maximum voltage level for control lines or data lines is +/- 25 positive V dc and
+/- 25 negative V dc. A timing or control line is active if the voltage is more than +3 V,
or inactive if the voltage is less than -3 V. The voltage reference point is the signal
ground on pin 7.
A data signal greater than +3 V means that the bit is a logical 0. A signal less than
-3 V means that the bit is logical 1.
For additional information, refer to
Interface between Data Terminal Equipment and
Data Communications Equipment Employing Serial Binary Data Interchange
,
published by the Electronic Industries Association, publications EIA RS-232C and
EIA\TIA-232-E.
9 to 25 Pin Cable Adapter,
Lexmark 1038693 (50 ft)
9 (F)
25 (M)
25 (M)
25 (F)
Shield
Shield
such as IBM 6450242 (10 in.)
