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You can review the output status in software to determine if the
current has exceeded the limit threshold.

You can configure each channel on the NI 9478 to disable the
output that exceeds the current limit threshold. Some applications
require a large inrush current that may exceed the current limit
threshold. You can disable overcurrent protection by setting no
current limit for that channel.

Caution

 

If you disable overcurrent protection, the

NI 9478 is no protected against overcurrent or short-
circuit conditions. Verify the wiring is correct and that
you are operating the NI 9478 within the specifications.

Overcurrent Refresh

The NI 9478 provides an overcurrent refresh setting. This setting
enables the channel to recover within a specified refresh period.
If the refresh setting is disabled, the channel remains off until it
receives a command from the software.

Safe Operating Conditions

The total amount of current that you can switch with a channel
depends on the duty cycle of the channel, the ambient

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NI 9478 Getting Started Guide

Summary of Contents for NI 9478

Page 1: ...GETTING STARTED GUIDE NI 9478 16 DO 0 V to 50 V Sinking 50 μs ...

Page 2: ... Refer to the documentation for each component in the system to determine the safety and EMC ratings for the entire system Safety Guidelines Operate the NI 9478 only as described in this document Caution Do not operate the NI 9478 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 damage...

Page 3: ...is for measurements performed on circuits not directly connected to the electrical distribution system referred to as MAINS voltage MAINS is a hazardous live electrical supply system that powers equipment This category is for measurements of voltages from specially protected secondary circuits Such voltage measurements include signal levels special equipment limited energy parts of equipment circu...

Page 4: ...es for Hazardous Locations The NI 9478 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 9478 in a potentially explosive environment Not following these guidelines may result in serious injury or death Caution Do not di...

Page 5: ...e across the external power supply and the COM pin The device must prevent the external power supply voltage from exceeding 70 V if there is a transient overvoltage condition Special Conditions for Hazardous Locations Use in Europe and Internationally The NI 9478 has been evaluated as Ex nA IIC T4 Gc equipment under DEMKO Certificate No 07 ATEX 0626664X and is IECEx UL 14 0089X certified Each NI 9...

Page 6: ...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 limi...

Page 7: ...ent 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 ...

Page 8: ...ling 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 9478 meets the following specifications Operating temperature IEC 60068 2 1 IEC 60068 2 2 40 C to 70 C Operating humidity IEC 60068 2 78 10 RH to 90 RH noncondensing Pollution Degree 2 Maximum altitude 2 000 m Indoor use only ...

Page 9: ...Note Refer to the device datasheet on ni com manuals for complete specifications NI 9478 Getting Started Guide National Instruments 9 ...

Page 10: ... DO8 DO9 DO10 DO11 DO12 DO13 DO14 DO15 NC COM COM COM COM COM COM COM COM Vsup Vsup COM COM COM COM COM COM COM COM 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 10 ni com NI 9478 Getting Started Guide ...

Page 11: ...up Voltage supply connection Connecting Digital Devices You can connect a variety of industrial devices such as solenoids motors actuators relays and lamps to the NI 9478 You must connect an external power supply to the NI 9478 The power supply provides the current for the output channels NI 9478 Getting Started Guide National Instruments 11 ...

Page 12: ...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 9478 are compatible with the output specifications of the NI 9478 Refer to the device datasheet at ni com manuals for output specifications 12 ni com NI 9478 Getting Started Guide ...

Page 13: ...evice does not have flyback protection install an external flyback diode Figure 2 Connecting a Flyback Diode NI 9478 COM DO External Power Supply Vsup Cable Clamp Device Cable Inductance The inductance of the cabling stores energy when a channel is on and driving current When a channel turns off energy in the NI 9478 Getting Started Guide National Instruments 13 ...

Page 14: ...ffective cable length is the total distance from DO to COM Figure 3 Cable Length of the NI 9478 NI 9478 COM Vsup DO External Power Supply Cable Length Load Cable Clamp NI recommends adding a capacitor across the power supply leads and a diode from the DO lead to the Vsup lead Connecting a capacitor and a diode reduces the effective cable length and dissipated heat 14 ni com NI 9478 Getting Started...

Page 15: ...that you use a capacitor with a capacitance of at least 20 µF I O Protection The NI 9478 provides protection against overcurrent and short circuit conditions Overcurrent Protection The NI 9478 provides two configurable current limit thresholds Limit A and Limit B The device monitors each output channel NI 9478 Getting Started Guide National Instruments 15 ...

Page 16: ...rrent protection the NI 9478 is no protected against overcurrent or short circuit conditions Verify the wiring is correct and that you are operating the NI 9478 within the specifications Overcurrent Refresh The NI 9478 provides an overcurrent refresh setting This setting enables the channel to recover within a specified refresh period If the refresh setting is disabled the channel remains off unti...

Page 17: ... ni com manuals for safe operating conditions You can determine safe operating specifications for the NI 9478 by using the following equation Figure 5 Safe Operating Conditions Equation 4 2 0 12 ℎ 0 2 2 0 04 1 where P is the percentage of total allowable power the channel uses Iout is the output current in amperes while the channel is on length is the total cable length in meters freq is the frequ...

Page 18: ...rrent through 2 0 meters of cable The channel cycles on for 40 μs and off for 10 μs for a total output period of 50 μs This yields an output frequency of 20 kHz using 14 8 of the total power budget Figure 6 Example Equation One 4 1 252 0 12 2 0 0 2 1 252 0 04 1 25 1 20 14 8 Example Two The NI 9478 is on and passing 3 A of current through 2 0 meters of cable for 0 25 seconds The channel passes 1 25...

Page 19: ...r budget The channel uses 14 8 of the total power budget driving at 20 kHz and 0 when the channel is off The total percentage of allowable power over the complete 5 5 second cycle is 5 Figure 7 Example Equation Two 36 0 25 14 8 1 25 0 4 5 5 5 NI 9478 Getting Started Guide National Instruments 19 ...

Page 20: ...ftware CompactRIO NI CompactDAQ RELATED INFORMATION NI 9478 Datasheet NI RIO Help LabVIEW FPGA Help NI 9478 Datasheet NI DAQmx Help LabVIEW Help C Series Documentation Resources ni com info cseriesdoc Services ni com services 20 ni com NI 9478 Getting Started Guide ...

Page 21: ...oduct Product registration facilitates technical support and ensures that you receive important information updates from NI A Declaration of Conformity DoC is our claim of compliance with the Council of the European Communities using the manufacturer s declaration of conformity This system affords the user protection for electromagnetic compatibility EMC and product safety You can obtain the DoC f...

Page 22: ...ucts technology refer to the appropriate location Help Patents in your software the patents txt file on your media or the National Instruments Patent Notice at ni com patents You can find information about end user license agreements EULAs and third party legal notices in the readme file for your NI product Refer to the Export Compliance Information at ni com legal export compliance for the NI glo...

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