Measurement Computing PCI-INT32 User Manual

Page 13

PCI-INT32 User's Guide

Functional Details

With a pull-down resistor installed, the line is pulled low when the Z8536 is reset. The Z8536 has more than
enough power to drive the line high.

To safeguard against unwanted signal levels, all devices that are controlled by the Z8536 chip should be tied
low or high as required by a 2.2K

Ω resistor. Open positions are located on the board to install resistor Single

Inline Packages (SIP). The positions are marked A, B, and C and are adjacent to the Z8536.

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 4-3

Figure 4-3. Eight-resistor SIP schematic

2.2KOhm SIP

Dot indicates the

common line

(LO or HI)

I/O Lines

Figure 4-4

Figure 4-4. Pull-up and pull-down resistor SIP schematic

shows a schematic of an SIP installed in both the pull-up and pull-down positions.

2.2 K SIP installed for pull-up

2.2 K SIP

Dot

+5 VDC

(GND)

Digi

l I/O

COM

Digital

I/O

Port

n = A, B, or C

2.2 K SIP

Dot

+5 VDC

(GND)

Digi

l I/O

COM

2.2 K SIP installed for pull-down

Digital

I/O

Port

n = A, B, or C

When installed, the SIP establishes either a high or low logic level at each of the eight I/O lines on the port. At
each board location, A, B, and C, there are 10 holes in a line. The hole on one end is marked "HI" and is
connected to +5V. The other end is marked "LO" and is connected to GND. The eight holes in the middle
connect to eight lines of the port, A, B or C.

To pull-up lines, orient the SIP with the common pin (dot) toward the HI end; to pull-down, install the resistor
with the common pin in the LO hole.

Note:
We recommend using 2.2K SIPs (MCC part number SP-K2.29C). Use a different value only if necessary.

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