Lexmark Dot Matrix Technical Reference - Page 100

The voltage reference point is the signal ground on pin 7. 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. A data signal more than +3 V means that the bit is a logical 0; less than -3 V means that the bit is a logical 1. For additional information, refer to the 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. Serial Data Frame Considerations (RS-232C) The computer sends serial data in data frames (also known as packets). You can create 10-bit, 11-bit, or 12-bit data frames and set the serial data transfer parameter so that each data frame contains 7 or 8 data bits. However, the printer is an 8-bit printer; characters, controls, and APA graphics need 8 bits of data. If you select 7-bit data transfer, some unexpected characters might print. Data Transmission Data transfer rates (in bits per second): • 300 bps • 600 bps • 1200 bps • 2400 bps • 4800 bps • 9600 bps • 19200 bps Start and Stop Bits The printer receives data with 1 start bit and either 1 or 2 stop bits. The printer always sends 1 start and 2 stop bits. Parity There are four possible parity settings: Even, Odd, No, and Ignore. When Even parity is selected, the printer expects to receive data frames with an even number of logical 1's per byte. The printer transmits data with even parity. When Odd parity is selected, the printer expects to receive data frames with an odd number of logical 1's per byte. The printer transmits data with odd parity. 100 Section 6: Using the Printer Interface