OMB-DAQ-2408 Series User's Guide
Functional Details
19
External pull-up/pull-down capability
You can also place an external pull-up resistor on any of the DIO bits, which enables you to pull the DIO bit up
to a voltage that exceeds the in5 V pull-up voltage.
When using external pull-up resistors, be aware of the following:
You should either remove the J6 jumper, or store it by attaching it to one of the three pins.
When using external pull-up resistors, be aware that the internal resistors cause a slight voltage impedance
shift to digital lines in the "on" state as various lines change between the on/off states.
Figure 13. Digital I/O external resistor configuration
Counter input
The
CTR0
and
CTR1
terminals are 32-bit event counters that can accept frequency inputs up to 1 MHz. The
internal counter increments when the TTL levels transition from low to high.
Ground
The analog ground (
AGND
) terminals provide a common ground for all analog channels.
The digital ground (
GND
) terminals provide a common ground for the digital and counter channels and the
power terminal.
47 k
Ω
DIO0
DIO1
DIO2
DIO3
DIO4
DIO5
DIO6
DIO7
+5 V
+ V
External pull-up resistor
J6
Internal jumper
disabled (placed on
center pin only)
