Lexmark 21Z0294 Technical Reference - Page 315

8-13 Interfaces The following illustration shows the pin assignments for the 9-pin to 25-pin IBM EIA RS-232C serial cables. 9 to 25 Pin Cable Adapter, such as IBM 6450242 (10 in.) Lexmark 1038693 (50 ft) Shield Shield 9 (F) 25 (M) 25 (F) 25 (M) 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.