Hardware Manual - RTD Embedded Technologies, Inc.

JS1, JS2, JS3, and JS4—Pull-Up/Pull-Down Resistors on Digital I/O Lines
The DM6425HR has 32 TTL/CMOS compatible digital I/O lines that can be interfaced with external devices.
These lines are divided into four groups: Port 0 has eight bit programmable lines, advanced interrupt modes, and
bit masking, Port 1 is byte direction programmable, Port 2 is output, and Port 3 is latched input. Resistors are
connected to these lines and can be configured as either pull-up or pull-down resistors.
10 kΩ pull-up/pull-down resistors are installed on the DM6425HR, and a solder connection must be made on
the bottom of the board to configure their operation. The solder connections are made at JS1 for Port 0, JS2 for
Port 1, JS3 for Port 3, and JS4 for Port 2. The factory default is pull-up for all ports. This is done by placing a solder
short between the middle (common) pad and V (+5 V). To configure the resistors as pull-down resistors, remove
the existing solder connection and make one between the middle (common) pad and G (ground). To disable the
pull-up/pull-down resistor, remove the solder connection.
WARNING Do not solder all three pads; doing so will damage the board!
G
G
V
V
Figure 10
JS1 and JS2 Pull-Up/Pull-Down Resistor Connections
V
V
G
G
Figure 11
JS3 and JS4 Pull-Up/Pull-Down Resistor Connections
18 DM6425HR dataModule BDM-610010034 Rev C