Measurement Computing USB-1208FS-Plus-OEM User Manual page 14

USB-1208FS-Plus-OEM User's Guide
When configured for input, the digital I/O terminals can detect the state of any TTL-level. Refer to the
schematic shown in Figure 6.
Figure 6. Schematic showing switch detection by digital channel Port A0
If you set the switch to the +5V input, Port A0 reads TRUE (1). When set to GND, Port A0 reads FALSE (0).
Pull-up/down configuration
All digital I/O lines are pulled high to USB +5 V with a 47 kΩ resistor by default. You can change the
pull-up/down configuration using the internal jumper labeled
access the jumper on the circuit board.
Complete the following steps to set the jumper for pull-up or pull-down:
1. Unplug the device from the computer.
2. Turn the device over and rest the top of the housing on a flat, stable surface.
Caution! The discharge of static electricity can damage some electronic components. Before removing the
USB-1208FS-Plus-OEM from its housing, ground yourself using a wrist strap or touch the
computer chassis or other grounded object to eliminate any stored static charge.
3. Remove the three screws from the bottom of the device using a #1 Philips head screwdriver.
4. Hold both the top and bottom sections together, turn the device over and rest it on the surface, then
carefully remove the top section of the case to expose the circuit board.
The user-configurable jumpers are labeled
the circuit board.
5. Set each jumper for pull-up (P/UP) or pull-down (P/DN), as shown in Figure 8. Use the jumper labeled
to configure Port A, and
DIO A
6. Replace the top section of the housing, and fasten it to the bottom section with the three screws.
and
DIO A
1 DIO B jumper 2
Figure 7. Pull-up/down jumper locations
to configure Port B.
DIO B
Figure 8. Pull-up/down jumper configuration
14
. You must remove the device housing to
DIO
. Figure 7 shows the location of each jumper on
DIO B
DIO A jumper
Functional Details