11
12
3.2.2 Jumpers K1 and K2
The internal jumpers mounted on the Model 2003’s PC board
(labeled K1 - K2) are used to configure the RS-232/RS-485 operation
and keyboard operation. Figure 7 (below) shows the location of the
Model 2003’s jumpers on the internal PC board.
Jumper K1: RS-232 or RS-485 Interface
This setting determines whether the the DB-25 operates according
to the RS-232 standard or the RS-485 standard.
K1
Setting
1 & 2
RS-232 Operation
(default position)
2 & 3
RS-485 Operation
Jumper K2: Power via DB-25 Pin 9
Normally, the Model 2003 operates on +5V supplied by the 6 pin
computer’s Mini-DIN keyboard interface. You may also supply operat-
ing voltage to pin 9 on the DB-25 connector if you don’t connect the
computer’s Mini-DIN keyboard interface. However, most computers
already supply voltage on pin 9. DO NOT connect this jumper unless
you are not connecting the computer keyboard port AND the RS-232
device does not supply power.
K2
Setting
Strap On
Co5V from the RS-232 device to pin 9 of the
DB-25 connector
Strap Off
Disconnects pin 9 on the DB-25 connector
(default position)
Switch K1
Switch K2
Figure 8. Possible strap positions for jumper K1
Figure 7. Jumpers K1 and K2 on the top of Model 2003 pc board
Rear
Front
1
2
3
1 2
1
2
3
1
2
3
Default
RS-232
RS-485
Toward
Rear
WARNING!! +5V is normally provided by the PC. DO NOT
connect to a5V source if the PC provides power. This
can result in damage to the RS-232 device and to connecting
equipment.
