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National Instruments Corporation
17
NI 6520/6521 User Guide
To connect to the NI 6520/6521 signals for Form A relays, connect NO and
COM, as shown in Figure 11.
Figure 11.
Relay Signal Connection Example for Form A Relays
Power Connections
Isolation Circuitry
Input Isolation Circuitry
The optocouplers optically isolate the NI 6520/6521 digital input channels.
Each IC has an optocoupler that provides optical isolation for one channel
of input.
Output Isolation Circuitry
The electromechanical relays provide isolation on the NI 6520/6521 output
channels. Each relay provides isolation at one channel of output.
Isolation Voltages
NI 6520 Isolation Voltages
The terminals of each I/O channel are isolated from other I/O channels,
from the connector shell, and digital ground. Isolation barriers provide
isolation up to 30 Vrms/42.4 V
pk
/60 VDC between any two terminals,
except between the two terminals making up a single digital I/O channel.
Caution
Do
not
exceed the isolation voltage limits. Exceeding the voltage limits may
cause injury or permanently damage the NI 6520 components. National Instruments is
not
liable for any damage resulting from signal connections that exceed these limits.
Load
P1.
X
COM
P1.
X
NO
Power