Chapter 3 Signal Connections
6527 User Manual 3-12 www.ni.com
Overcurrent Protection
The 6527 device outputs include circuitry to protect them from currents
over the specified range. When excessive current flows through the relay,
the relay increases resistance. Once the current level drops back under the
specified range, the relays return to normal operation.
The overcurrent protection ratings for a 6527 device are as follows
(typical at 25 °C):
• Overcurrent protection limit = 260 mA
• Current limit time = 1 µs at 7 V
• Duration of current above operating current (120 mA): 1 s max at 7 V
Caution Overcurrent protection is for protection against transient fault conditions only.
The 6527 should not normally be operated above 120 mA. National Instruments is not
liable for any damages resulting from signal connections that exceed 120 mA.
Power-on and Power-off Conditions
At power-up, the initial state of the digital output lines are logic high and
the solid-state relays are open. The solid-state relays are also open when the
computer and the 6527 device are powered off.