©
National Instruments Corporation
9
Getting Started with the NI PCIe-8255R
Specifications
The following specifications apply to the NI 8255R image acquisition device. These specifications are
typical at 25 °C, unless otherwise stated.
TTL Inputs and Outputs
Digital logic levels
TTL Inputs
Number of channels ...............................................2
Maximum pulse rate ..............................................2 MHz
Minimum pulse detected........................................500 ns
Power-on state........................................................Input (high-impedance) 61.9 k
Ω
pull-up to 5 V
TTL Outputs
Number of channels ...............................................10
Output voltage range..............................................0 V to 5 V
Maximum pulse rate ..............................................2 MHz
Optically Isolated Inputs and Outputs
Isolated (Current Sinking) Inputs
Number of channels ...............................................13
Input voltage range ................................................0 V to 30 V
Input ON voltage............................................3.5 V to 30 V
Input OFF voltage ..........................................0 V to 2 V
Turn-on current ..............................................7.1 mA, typical
14 mA, maximum
Maximum pulse rate ..............................................100 kHz
Minimum pulse detected........................................10
μ
s
Reverse polarity protection ....................................Yes, –30 V
Isolated (Current Sourcing) Outputs
Number of channels ...............................................4
On-state voltage range ...........................................5 V to 30 V, maximum
Maximum on-state voltage
drop from V ...................................................1.2 V at 100 mA
Level
Minimum
Maximum
Input low voltage (V
IL
)
0 V
0.5 V
Input high voltage (V
IH
)
2.2 V
5 V
Output low voltage (V
OL
), at 5 mA
—
0.4 V
Output high voltage (V
OH
), at 5 mA
2.4 V
—
