SC-2061 Board
Chapter 3
SC-206X Series User Manual
3-2
© National Instruments Corporation
The output channels are labeled OUT0 through OUT7 at the screw terminals. The SC-2061 has
three screw terminals per channel–GND, OUTx , where x is any channel number (0 through 7), and
+5 V. The lines b5 V and GND indicate the boundary between channels.
The digital output of the SC-2061 is positive logic; that is, high output states from the data
acquisition board create high output at the screw terminals. The SC-2061 has eight channels of
optocoupler output. The digital output signal and its reference ground must connect at the screw
terminals. A +5 VDC power supply must also connect at the screw terminals. The digital output
signal must be pulled up. National Instruments recommends using a 4.7 k
Ω
resistor to the
+5 VDC line for the SC-2061. Because the output lines are open-collector lines, you must use
pullup resistors to obtain valid output from the board. Figure 3-2 shows the 5 V onboard
equivalent circuit for the SC-2061 board.
GND (isolated)
Recommended pullup
resistor to be installed
by user to get valid
TTL levels at OUT
L5541
20
A
X
From
plug-in
board
Y
X
HPCL-2611-060
Opto-coupler
270
OUT (isolated)
+5 V (isolated)
SC-2061 Field Connections
(single channel is shown)
DIO
X
Ω
IN4148
IN4148
+5 V
GND (isolated)
4.7 k
OUT (isolated)
+5 V (isolated)
Ω
Figure 3-2. SC-2061 Onboard Equivalent Circuit
Warnings: When connecting or disconnecting signal lines to the screw terminals, you must power
off the lines. Potential differences between the lines and the SC-2061 ground create a
shock hazard while connecting the lines.
Connections, including power signals to ground and vice versa, that exceed any of the
maximum input or output signal ratings on the SC-2061 board can result in damage to
any or all of the boards connected to the SC-206X Series, to the host computer, and to
the SC-2061 board. National Instruments is not liable for any damages resulting from
incorrect signal connections.
