Serial Port Jumpers - Sun Microsystems Ultra 1 Series Reference Manual

4.3

Serial Port Jumpers

The serial port jumpers on the main logic board permit configuring the two DB-25
serial ports on the system unit back panel for either RS-423 or RS-232 signal levels.
RS-423 levels are the default standard for North American users. RS-232 levels are
required for digital telecommunication in nations of the European Community.
TABLE 4-2
Jumper Pins 1 + 2 Select
J2104 RS-232
J2105 RS-232
Note – In an Ultra 1 Series system, jumper J2104 is not marked with an asterisk to
indicate pin 1. The pins are numbered in the way shown in
Figure 4-3 in relation to the J2104 marking on the main logic board.
3 2
FIGURE 4-3
4-4 Sun Ultra 1 Series Reference Manual • September 1995
Serial Port Jumper Settings
Pins 2 + 3 Select
RS-423
RS-423
1
J2104
Ultra 1 Series, Jumper J2104 Pin Numberin
Default Shunt
on Pins Signal Controlled
2 + 3 RS232/RS423 SEL
2 + 3 RS232/RS423 SEL