DirecTV DTV-MD0-0058 - Manual (Page 9)

DIRECTV Set-top box information for the installer
DIRECTV Proprietary November 17, 2005
Version 1.1.a Page 9 of 49 DTV-MD-0058
Figure 1. Low-Speed Data Port Pin Assignment Diagram
Figure 2. Orientation of the RJ22 (4 way/4 position) Jack
3.2 Low-Speed Data Port Interface
The STB low-speed data port is a PC compatible serial port, and functions as a subset of RS-574.
The intended use is for direct connection to a PC or other equipment, allowing exchange of
control and data between the STB and that equipment using specialized software. For successful
communications with the STB, some PC serial port interface cards may require that their flow
control lines be strapped internally as “enabled,” and thus disconnected from any external flow
control signaling. Additionally, those PC serial ports incorporating a buffered 16550 UART
may be least likely to experience communications problems.