Lexmark C752 Technical Reference page 337

8-28
Interfaces
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.
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, and 12-bit data frames and set the serial data transfer parameter
so that each data frame contains 7 or 8 data bits. However, your printer is an 8-bit
printer; characters, controls, and all points addressable (APA) graphics need 8 bits of
data. If you select 7-bit data transfer, some unexpected characters might print.
Data Transmission
The list of acceptable data transfer rates (in bits per second) can be accessed from
the printer operator panel or through MarkVision Professional. Refer to your printer
user documentation for more information.
Data Bits
The printer sends or receives 7 or 8 data bits in each transmission frame, depending
on which one is selected.