PCI-DIO48H User's Guide
Functional Details
Pull-up and pull-down resistors
The PCI-DIO48H board has open locations where you can install a 2.2 K
Ω
, eight-resistor single inline
package (SIP) resistor network for each port. The locations are marked
A
,
B
or
C
in the
PORT 1
or
PORT 2
area on the board (RN6 through RN11), and are adjacent to the I/O connectors.
The SIP is made up of eight 2.2 K resistors. One side of each resistor is connected to a single common
point and brought out to a pin. The common line is marked with a dot or line at one end of the SIP. The
remaining resistor ends are brought out to the other eight pins (refer to
).
Figure 4-2
Figure 4-2. Eight-Resistor SIP Schematic
2.2 KOhm SIP
Dot
(LO or HI)
I/O Lines
The SIP may be installed as pull-up or pull-down. At each RN# location, there are 10 holes in a line. One
end of the line is +5V, the other end is GND. They are marked
HI
and
LO
respectively. The eight holes in
the middle are connected to the eight lines of a port.
For a pull-up function, mount the SIP with the common pin (marked with a dot or line) in the
HI
position.
For a pull-down function, mount the SIP with the common pin in the
LO
position.
When installing pull-up and pull-down resistor SIP packs, we recommend using a 2.2 K, eight-resistor
SIP (MCC part number SP-K2.29C).
Unconnected inputs float
Unconnected inputs typically float high, but not reliably. If you are using a PCI-DIO48H board for input
and have unconnected inputs, ignore the data from those lines. You do not have to terminate input lines.
Unconnected lines will not affect the performance of connected lines. Ensure that you mask out any
unconnected bits in software.
4-2
Summary of Contents for PCI-DIO48H
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