NI-9351 Getting Started

The analog input signals are scanned, amplified, conditioned, and then sampled by two independent ADCs. The module provides overvoltage protection for each channel. Only one channel can be in an overvoltage condition at a time.

You must connect an external power supply to the NI-9351. The module is independent from the chassis and requires an external power supply to operate.

Connect the positive lead of the power supply to the supply pin, V_sup, and the negative lead of the power supply to any common pin, COM.

The NI-9351 has current sourcing outputs, meaning the DO pin is driven to V_sup when the channel is turned on.

Refer to the following diagrams to connect the NI-9351 based on the I/O configurations in the Functional Safety Editor. For more information about I/O Configurations, refer to the C Series Functional Safety Manual on ni.com/manuals.

• Use this diagram for single input and dual input configurations.
• Use one of the following pairs for dual switches: DI0 and DI1, DI2 and DI3.

• Use this diagram for single input with test pulse configurations.
• Use test pulses to detect wiring faults on NC (normally closed) switches.
• Connect the DO pin to the NC (normally closed) switch to provide test pulse output.

• Use this diagram for dual input with test pulse configurations.
• Use one of the following pairs for dual switches: DI0 and DI1, DI2 and DI3.
• Use test pulses to detect wiring faults on NC (normally closed) switches.

• Use this diagram for the following configurations:
  • Single output
  • Dual output
  • Single output with internal test pulse
  • Dual output with internal test pulse

• Use this diagram for single output with external test pulse and dual output with external test pulse configurations.
• Connect a wire from the external monitoring location to a DI channel to monitor the test pulse.
• Connect the DI channel number that corresponds to the DO channel number. Single output with test pulse connections use DOn and DIn. Dual output with test pulse connections use DOn and DIn, DOn+1 and DIn+1.

• Use this diagram for single output with external readback configurations.
• Connect a wire from the external monitoring location to a DI channel to monitor the output value.

Users must use a limited power source (LPS) supply suitable to the safety needs and configuration of the implemented system. Implement one of the following options to ensure continued compliance with IEC 61010-1.

• The Vsup must be powered from a Class 2 or Limited Power Source (LPS), SELV source, 30 V DC maximum.
• The Vsup must be powered from a SELV source, 30 V DC maximum, with supplementary overcurrent protection in series, 8 A maximum breaking capacity at 120 s.
• The C Series Functional Safety module and associated controller must be installed in an end-use fire enclosure.

• NI recommends connecting an external 3 kΩ pull-down resistor to each digital input channel in use.
• Resistor power must be rated at minimum to 300 mW at system ambient temperatures. A larger rating can increase reliability.
• A pull-down resistor reduces input signal response times when channels are driven by sourcing outputs.
• The user is responsible for evaluating and choosing the appropriate resistor and terminal block based on the system requirements.
• Follow mounting and thermal guidelines in the CompactRIO controller documentation.

Refer to the table below for suggested terminal blocks for mounting the resistor.

Install an external flyback diode on any digital output connection to inductive or energy-storing devices that do not have flyback protection. Inductive or energy storing devices include solenoids, motors, and relays.

If your application is subject to high vibration, NI recommends that you use ferrules to terminate stranded wire.

You must follow these guidelines to meet the shock and vibration performance specifications stated in the device datasheet on ni.com/manuals.

• Panel mount the system.
• Provide strain relief for the module by securing the cabling to a supporting fixture no more than 8 cm (3 in.) away from the opening of the connector backshell.
• Ensure that the supporting fixture for strain relief is stiff and rigidly coupled to the chassis mounting surface.
• Ensure that you do not directionally bias the module when applying strain relief.

The NI-9351 provides overcurrent and short-circuit protection for each DO channel.

The NI-9351 provides overvoltage protection for each AI channel.

Some overvoltage conditions may cause an internal temperature fault, forcing the module into Fail-safe Mode. Conditions that may cause an internal temperature fault include:

• A fault on a single channel exceeding 20 V
• Faults on multiple channels

For fault voltage derating above 55 °C, refer to the device datasheet on ni.com/manuals.

The NI-9351 has an internal temperature sensor that will cause the module to enter Fail-safe Mode if the internal temperature limit is exceeded.

This document provides information about connecting and installing the NI-9351 hardware. You must download a compiled User Program before deployment. For information about creating User Programs, deploying safety systems using the NI-9351, and diagnostics available on the NI-9351, go to ni.com/info and enter Info Code safetymanual.