Lexmark Printer User Manual page 375

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Interfaces
Serial Communication Parameters (RS-422)
The following paragraphs show acceptable values for serial communication
parameters.
Voltage Level
RS-422 serial interface uses a differential pair, 5-volt typical delta, 0.5 volt threshold.
Your printer uses a TI75179 transceiver with transorbs. The polarity of the signals is
programmable.
Serial Data Frame Considerations
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, your 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
The list of acceptable data transfer rates (in bits per second) can be accessed from
your printer operator panel or through MarkVision Professional. Refer to your printer
user documentation for more information.
Data Bits
Your printer sends or receives 7 or 8 data bits in each transmission frame, depending
on which one is selected.
Start and Stop Bits
Your printer receives data with 1 start bit and either 1 or 2 stop bits. The printer always
sends 1 start and 2 stop bits.