NI 9474 Getting Started Guide

Safety Guidelines

Operate the NI 9474 only as described in this document.

[Caution] Do not operate the NI 9474 in a manner not specified in this document. Product misuse can result in a hazard. You can compromise the safety protection built into the product if the product is damaged in any way. If the product is damaged, return it to NI for repair.

[Hazardous Voltage] This icon denotes a warning advising you to take precautions to avoid electrical shock with the NI 9474 with screw terminal and the NI 9474 with spring terminal.

Safety Voltages

Connect only voltages that are within the following limits.

Measurement Category II is for measurements performed on circuits directly connected to the electrical distribution system.

This category refers to local-level electrical distribution, such as that provided by a standard wall outlet, for example, 115 V for U.S. or 230 V for Europe.

[Caution] Do not connect the NI 9474 to signals or use for measurements within Measurement Categories III or IV.

Safety Guidelines for Hazardous Voltages

If hazardous voltages are connected to the device, take the following precautions. A hazardous voltage is a voltage greater than 42.4 Vpk voltage or 60 VDC to earth ground.

• [Caution] Ensure that hazardous voltage wiring is performed only by qualified personnel adhering to local electrical standards.
• [Caution] Do not mix hazardous voltage circuits and human-accessible circuits on the same module.
• [Caution] Ensure that devices and circuits connected to the module are properly insulated from human contact.
• [Note] When module terminals are hazardous voltage LIVE (>42.4 Vpk/60 VDC), you must ensure that devices and circuits connected to the module are properly insulated from human contact. You must use the NI 9927 connector backshell kit with the NI 9474 with screw terminal and the NI 9981 connector backshell kit with the NI 9474 with spring terminal to ensure that the terminals are not accessible.

Safety Guidelines for Hazardous Locations

The NI 9474 is suitable for use in Class I, Division 2, Groups A, B, C, D, T4 hazardous locations; Class I, Zone 2, AEx nA IIC T4 and Ex nA IIC T4 hazardous locations; and nonhazardous locations only. Follow these guidelines if you are installing the NI 9474 in a potentially explosive environment. Not following these guidelines may result in serious injury or death.

• [Caution] Do not disconnect I/O-side wires or connectors unless power has been switched off or the area is known to be nonhazardous.
• [Caution] Do not remove modules unless power has been switched off or the area is known to be nonhazardous.
• [Caution] Substitution of components may impair suitability for Class I, Division 2.
• [Caution] For Division 2 and Zone 2 applications, install the system in an enclosure rated to at least IP54 as defined by IEC/EN 60079-15.
• [Caution] For Division 2 and Zone 2 applications, install a protection device between the Vsup and COM terminals on the NI 9474. The device must prevent the input Vsup-to-COM voltage from exceeding 42 V if there is a transient overvoltage condition.

Special Conditions for Hazardous Locations Use in Europe and Internationally

The NI 9474 has been evaluated as Ex nA IIC T4 Gc equipment under DEMKO Certificate No. 03 ATEX 0324020X and is IECEx UL 14.0089X certified. Each NI 9474 is marked & II 3G and is suitable for use in Zone 2 hazardous locations, in ambient temperatures of -40 °C ≤ Ta ≤ 70 °C. If you are using the NI 9474 in Gas Group IIC hazardous locations, you must use the device in an NI chassis that has been evaluated as Ex nC IIC T4, Ex IIC T4, Ex nA IIC T4, or Ex nL IIC T4 equipment.

• [Caution] You must make sure that transient disturbances do not exceed 140% of the rated voltage.
• [Caution] The system shall only be used in an area of not more than Pollution Degree 2, as defined in IEC 60664-1.
• [Caution] The system shall be mounted in an ATEX/IECEx-certified enclosure with a minimum ingress protection rating of at least IP54 as defined in IEC/EN 60079-15.
• [Caution] The enclosure must have a door or cover accessible only by the use of a tool.

Electromagnetic Compatibility Guidelines

This product was tested and complies with the regulatory requirements and limits for electromagnetic compatibility (EMC) stated in the product specifications. These requirements and limits provide reasonable protection against harmful interference when the product is operated in the intended operational electromagnetic environment.

This product is intended for use in industrial locations. However, harmful interference may occur in some installations, when the product is connected to a peripheral device or test object, or if the product is used in residential or commercial areas. To minimize interference with radio and television reception and prevent unacceptable performance degradation, install and use this product in strict accordance with the instructions in the product documentation.

Furthermore, any changes or modifications to the product not expressly approved by National Instruments could void your authority to operate it under your local regulatory rules.

Special Conditions for Marine Applications

Some products are Lloyd's Register (LR) Type Approved for marine (shipboard) applications. To verify Lloyd's Register certification for a product, visit ni.com/certification and search for the LR certificate, or look for the Lloyd's Register mark on the product.

[Caution] In order to meet the EMC requirements for marine applications, install the product in a shielded enclosure with shielded and/or filtered power and input/output ports. In addition, take precautions when designing, selecting, and installing measurement probes and cables to ensure that the desired EMC performance is attained.

Preparing the Environment

Ensure that the environment in which you are using the NI 9474 meets the following specifications.

Indoor use only.

[Note] Refer to the device datasheet on ni.com/manuals for complete specifications.

NI 9474 Pinout

The NI 9474 has two terminal types: screw terminal and spring terminal. The pinout is consistent for both.

Screw Terminal Pinout:

DO0: Terminal 0
DO1: Terminal 1
DO2: Terminal 2
DO3: Terminal 3
DO4: Terminal 4
DO5: Terminal 5
DO6: Terminal 6
DO7: Terminal 7
Vsup: Terminal 8
COM: Terminal 9

Spring Terminal Pinout:

DO0: Terminal 0
DO1: Terminal 1
DO2: Terminal 2
DO3: Terminal 3
DO4: Terminal 4
DO5: Terminal 5
DO6: Terminal 6
DO7: Terminal 7
Vsup: Terminal 8
COM: Terminal 9

Signal Descriptions and LED Indicators

[Note] You must use 2-wire ferrules to create a secure connection when connecting more than one wire to a single terminal on the NI 9474 with screw terminal or NI 9474 with spring terminal.

Connecting Digital Devices

You can connect a variety of industrial devices, such as solenoids, motors, actuators, relays, and lamps to the NI 9474. You must connect an external power supply to the NI 9474. The power supply provides the current for the output channels.

Figure 1. Connecting an Industrial Device to the NI 9474

This diagram shows the NI 9474 module with its Vsup, DO, and COM terminals. A device is connected between the DO terminal and COM. An external power supply is connected with its positive terminal to Vsup and its negative terminal to COM. The DO terminal is connected to the device.

[Caution] Do not install or remove C Series modules from your system if the external power supply connected to the Vsup and COM pins is powered on.

Ensure that the devices you connect to the NI 9474 are compatible with the output specifications of the NI 9474. Refer to the device datasheet on ni.com/manuals for output specifications.

[Note] When the industrial device is off, DO is not connected to COM. For large source impedances, you must use a pull-down resistor between DO and COM. Visit ni.com/info and enter the Info Code CSeriesDOPulseGen for more information.

Increasing Current Drive

Each channel of the NI 9474 has a continuous output current of 1.0 A. If you want to increase the output current to a device, you can connect any number of channels together in parallel. For example, if you want to drive 4 A of current, connect DO0 through DO3 in parallel. You must turn all parallel channels on and off simultaneously so that the current on any single channel cannot exceed the 1.0 A rating.

Figure 2. Increasing the Current to a Device Connected to the NI 9474

This diagram illustrates connecting multiple channels in parallel. The Vsup terminal is connected to the positive terminal of an external power supply. Channels DO0, DO1, DO2, and DO3 are each connected to a device, with a current rating of 1 A per channel. All these channels are connected together and to the device, allowing for a total of 4 A. The COM terminal is connected to the negative terminal of the external power supply and to the device.

High-Vibration Application Connections

If your application is subject to high vibration, NI recommends that you follow these guidelines to protect connections to the NI 9474:

• Use ferrules to terminate wires to the detachable connector.
• Use the NI 9927 backshell kit with the NI 9474 with screw terminal or the NI 9981 backshell kit with the NI 9474 with spring terminal.

I/O Protection

The NI 9474 provides short-circuit protection. Each channel has circuitry that protects it from current surges resulting from short circuits over 14 A.

[Note] Refer to the device datasheet on ni.com/manuals for maximum continuous output current, short-circuit behavior, and short-circuit trip time specifications and information about conditions that may damage the module.

[Note] Refer to the IEC 61131-2 standard for more information about short-circuit-proof devices.

[Note] Because the NI 9474 includes internal flyback diodes, you do not need to add external diodes when connecting to switching devices that store energy.

Power Supplies and Overcurrent Conditions

If a short circuit occurs, the current through DO can exceed the current rating for the power supply and the maximum continuous output current for the NI 9474.

If the power supply you are using with the NI 9474 cannot supply more than 14 A, the module may be damaged if a short circuit condition occurs.

Detecting an Overcurrent Condition

If a device connected to the module is not working while the channel is on, the module channel may be in an overcurrent state. Neither the software nor the module LEDs indicate if an overcurrent condition occurs. A channel LED may be on even if the channel is off because of an overcurrent condition.

To determine if the channel is in an overcurrent state, measure the voltage between DO and Vsup. If the voltage is equal to the voltage of the external power supply connected to the module, the channel is in an overcurrent state.

Resetting Channels after an Overcurrent Condition

After you have determined and fixed the cause of an overcurrent condition, reset the channel by turning it off. Alternatively, you can disconnect the external power supply from the chassis. However, doing so disconnects power from all the module channels. Normal operation can resume after you correct the overcurrent condition and reset the channel.

Where to Go Next

CompactRIO

• NI 9474 Datasheet
• NI-RIO Help
• LabVIEW FPGA Help

NI CompactDAQ

• NI 9474 Datasheet
• NI-DAQmx Help
• LabVIEW Help

RELATED INFORMATION

• C Series Documentation & Resources: ni.com/info cseriesdoc
• Services: ni.com/services

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