Chapter 3 Signal Connections
6527 User Manual 3-6 www.ni.com
Power Connections
Four of the pins on the I/O connector are not isolated. Pin 50 and pin 100
connect to GND, the computer ground reference. Pin 49 and pin 99 of the
I/O connector supply +5 V from the computer power supply via a
self-resetting fuse. The fuse resets automatically within a few seconds after
an overcurrent condition is removed. The +5 V pins are referenced to the
GND pins and can be used to power external digital circuitry that does not
require isolation.
• Power rating: 1 A at +4.5 to +5.25 V
Warning The power pins, +5 V and GND, are not isolated; they connect to your computer
power supply. Never connect a +5 V power pin directly to GND. Never connect a +5 V or
GND pin to any other voltage source; doing so can lead to injury. National Instruments is
not liable for any damages or injuries resulting from such a connection.
Pin Signal Name Description
83, 85, 87, 89,
91, 93, 95, 97 DIG+3.<7..0> Isolated output port 3, first terminals—Each of these is the first
of two terminals of a bidirectional solid-state relay. A logic low
(data bit of 0) closes the relay.
84, 86, 88, 90,
92, 94, 96, 98 DIG–3.<7..0> Isolated output port 3, second terminals—Each of these is the
second of two terminals of a bidirectional solid-state relay.
A log ic low (data bit of 0) closes the relay.
67, 69, 71, 73,
75, 77, 79, 81 DIG+4.<7..0> Isolated output port 4, first terminals—Each of these is the first
of two terminals of a bidirectional solid-state relay. A logic low
(data bit of 0) closes the relay.
68, 70, 72, 74,
76, 78, 80, 82 DIG–4.<7..0> Isolated output port 4, second terminals—Each of these is the
second of two terminals of a bidirectional solid-state relay.
A log ic low (data bit of 0) closes the relay.
51, 53, 55, 57,
59, 61, 63, 65 DIG+5.<7..0> Isolated output port 5, first terminals—Each of these is the first
of two terminals of a bidirectional solid-state relay. A logic low
(data bit of 0) closes the relay.
52, 54, 56, 58,
60, 62, 64, 66 DIG–5.<7..0> Isolated output port 5, second terminals—Each of these is the
second of two terminals of a bidirectional solid-state relay.
A log ic low (data bit of 0) closes the relay.
Table 3-2. Signal Descriptions for 6527 Device I/O Connectors (Continued)