Product Introduction
The NI RMX-4125 is a high-power, single-channel programmable DC power supply designed for automated test, electronic validation, power electronics testing, production test, laboratory research, and other applications requiring flexible DC power delivery.
The RMX-4125 provides up to 1500 W of output power with programmable voltage from 0 VDC to 80 VDC and current from 0 A to 56 A. Its combination of high power, wide voltage and current operating ranges, remote programming interfaces, and compact 1U rack-mount construction makes it well suited for automated test equipment and rack-based measurement systems.
The power supply can be operated manually from the front panel or remotely through USB, LAN, RS232, and analog control interfaces, allowing it to be integrated into both interactive laboratory setups and fully automated test systems.
Product Overview
The National Instruments RMX-4125 is part of the NI RMX-412x family of rack-mount programmable power supplies.
It is designed for applications that require substantial DC power while maintaining programmable control over voltage and current.
- 1500 W maximum output power
- 0 VDC to 80 VDC programmable output
- 0 A to 56 A programmable current
- Single-channel DC output
- 1U rack-mount form factor
- Full rack width
- USB remote control
- LAN remote control
- RS232 remote control
- Analog control
- Front-panel controls
- Constant-voltage and constant-current operation
Key Features
1500 W Maximum Output Power
The RMX-4125 provides up to 1500 W of total DC output power.
This high-power capability makes it suitable for applications that require significantly more power than conventional benchtop or modular low-power supplies.
Typical applications include:
- Power electronics testing
- Automotive electronics validation
- Industrial equipment testing
- High-power electronic device testing
- Production test systems
- Research and development
- Automated test equipment
0 VDC to 80 VDC Programmable Output
The RMX-4125 provides a programmable DC output voltage range from 0 VDC to 80 VDC.
The broad voltage capability allows engineers to use the power supply with many different electronic devices and subsystems without requiring multiple fixed-voltage power supplies.
Up to 56 A Output Current
The RMX-4125 provides programmable current capability up to 56 A.
The combination of up to 80 VDC and up to 56 A provides flexibility for testing loads with different voltage and current requirements while operating within the supply’s overall power envelope.
Flexible Voltage and Current Operation
The RMX-4125 provides flexible voltage and current limits rather than operating at only one fixed voltage-current combination.
This makes the power supply suitable for test systems that must support multiple DUT configurations and operating conditions.
The actual available voltage and current combination is constrained by the maximum output capability and total output power of the power supply.
Constant-Voltage Operation
The RMX-4125 supports constant-voltage (CV) operation.
In constant-voltage mode, the power supply regulates its output to maintain the programmed voltage while the load current varies within the configured operating limits.
This mode is commonly used for:
- Electronic device power
- DUT validation
- Production testing
- Board-level testing
- System power simulation
Constant-Current Operation
The RMX-4125 also supports constant-current (CC) operation.
In constant-current mode, the power supply regulates the output current according to the programmed current setting while the output voltage adjusts according to the connected load and configured limits.
Automatic CV and CC Operating Behavior
The operating mode of the RMX-4125 depends on the programmed voltage, programmed current, and connected load resistance.
The power supply automatically operates in the appropriate constant-voltage or constant-current region according to these conditions.
This behavior allows the RMX-4125 to provide controlled power while protecting the DUT from exceeding configured voltage or current limits.
Single-Channel DC Power Supply
The RMX-4125 provides one programmable DC output channel.
The single-channel architecture concentrates the available output power into one high-power source, making the unit particularly suitable for DUTs and subsystems requiring substantial DC power.
1U Rack-Mount Form Factor
Despite providing up to 1500 W of output power, the RMX-4125 uses a compact 1U rack-mount form factor.
The low rack height helps conserve valuable rack space in automated test systems containing multiple instruments.
Typical rack systems may combine:
- RMX programmable power supplies
- PXI test systems
- Electronic loads
- Oscilloscopes
- Digital multimeters
- RF instruments
- Switching equipment
Full-Width Rack Design
The RMX-4125 is a full-width rack-mount power supply designed for integration into standard instrument racks and automated test installations.
Its rack-oriented architecture makes it particularly suitable for permanent production, validation, and laboratory test systems.
USB Remote Control
The RMX-4125 provides a USB interface for remote operation and automated control.
USB connectivity is useful for direct communication between the programmable power supply and a test computer.
LAN Remote Control
The RMX-4125 also provides LAN connectivity.
Ethernet-based control can be particularly useful in automated test environments where instruments are integrated through a laboratory or dedicated test network.
LAN connectivity can support:
- Remote instrument control
- Automated test systems
- Distributed test equipment
- Rack-mounted instrument networks
- Laboratory automation
RS232 Remote Control
An RS232 interface is available for applications that use serial communication for instrument control.
RS232 remains useful in many industrial and legacy automated test environments.
Analog Control
The RMX-4125 also provides analog control capability.
Analog control can be useful when output settings must be controlled by external analog signals or when integrating the power supply into specialized control architectures.
Front-Panel Operation
In addition to automated control interfaces, the RMX-4125 includes front-panel buttons and knobs for interactive operation.
This allows engineers to configure and operate the power supply manually during:
- System development
- Bench testing
- Troubleshooting
- Prototype validation
- Laboratory experiments
Calibration Utility
The RMX-4125 ships with a calibration utility to support maintenance and calibration-related workflows.
Calibration is particularly important in automated test and measurement environments where the accuracy and traceability of programmable power equipment must be maintained over time.
Technical Specifications
| Parameter | Description |
|---|---|
| Product Type | Programmable DC Power Supply |
| Model | NI RMX-4125 |
| Part Number | 784766-01 |
| Maximum Output Power | 1500 W |
| Output Voltage Range | 0 VDC to 80 VDC |
| Output Current Range | 0 A to 56 A |
| Number of Output Channels | 1 |
| Operating Modes | Constant Voltage / Constant Current |
| Rack Height | 1U |
| Rack Width | Full Width |
| USB Control | Supported |
| LAN Control | Supported |
| RS232 Control | Supported |
| Analog Control | Supported |
| Front-Panel Control | Buttons and Knobs |
| Nominal AC Input | 100 VAC to 240 VAC, 50 Hz to 60 Hz, Single Phase |
| AC Input Voltage Range | 85 VAC to 265 VAC |
| Input Frequency Range | 47 Hz to 63 Hz |
| Operating Temperature | 0 °C to 50 °C |
| Operating Environment | Indoor Use |
| Maximum Operating Altitude | 2,000 m |
| Primary Applications | Automated Test, Power Electronics, Production Test and Electronic Validation |
What Is a Programmable DC Power Supply?
A programmable DC power supply provides controlled DC voltage and current that can be adjusted manually or through software.
Unlike a fixed power supply, programmable models such as the RMX-4125 allow automated test software to modify output conditions during a test sequence.
A typical automated workflow can be represented as:
Test Software → RMX-4125 → DUT → Measurement Instruments → Test Results
The test system can automatically change the DUT supply voltage, set current limits, perform measurements, and determine whether the DUT meets its required specifications.
Why Use a 1500 W Programmable Power Supply?
High-power electronic devices and subsystems can require substantially more power than standard laboratory power supplies can provide.
The 1500 W output capability of the RMX-4125 makes it suitable for applications such as:
- High-power electronic assemblies
- Automotive electronics
- Power converters
- Industrial electronics
- Communication equipment
- Embedded systems
- Production test fixtures
Power Electronics Testing
The RMX-4125 can provide programmable DC power for compatible power electronics devices and systems.
Typical DUTs may include:
- DC-DC converters
- Power conversion modules
- Power distribution systems
- Industrial power electronics
- Electronic control systems
- High-power circuit assemblies
Engineers can program different input voltage and current conditions to evaluate DUT operation across its intended operating range.
Automotive Electronics Testing
Automotive electronic systems often require programmable DC power sources for design validation and production testing.
The RMX-4125 can be incorporated into automated automotive test systems for compatible devices such as:
- Electronic control units
- Power distribution modules
- Automotive electronic assemblies
- DC-powered control systems
- Vehicle electronic subsystems
The programmable output allows engineers to reproduce different DC supply conditions during validation.
Electronic Device Validation
During product development, engineers frequently need to evaluate device performance at multiple supply voltages and current conditions.
The RMX-4125 can automate these tests by allowing software to program the DC output during a validation sequence.
A typical sequence may include:
- Configure the initial output voltage.
- Set the required current limit.
- Enable the power supply output.
- Measure DUT performance.
- Change the voltage or current condition.
- Repeat measurements.
- Record the test results.
Production Test Applications
Production test systems require repeatable and programmable power sources that can be controlled automatically.
The RMX-4125 can provide DC power to a DUT while test software coordinates other measurement equipment.
Typical production test functions include:
- DUT power-up
- Voltage margin testing
- Current-limit testing
- Functional validation
- Power consumption testing
- Automated pass/fail testing
Rack-Mount Automated Test Systems
The 1U rack-mount architecture makes the RMX-4125 suitable for integration into complete automated test racks.
A typical system can include:
- NI RMX-4125 programmable power supply
- PXI or PXIe chassis
- PXI controller
- Digital multimeter
- Oscilloscope or digitizer
- DAQ modules
- Switching modules
- Electronic loads
- Communication interfaces
The power supply provides DUT power while the PXI instruments perform measurement, switching, communication, and data acquisition functions.
RMX-4125 with PXI Test Systems
Although the RMX-4125 is not a PXI module, it can be integrated with a PXI automated test platform through its remote communication interfaces.
A typical configuration can be represented as:
PXI Controller / Test Computer → USB, LAN or RS232 → RMX-4125 → DUT
Other PXI instruments can simultaneously acquire voltage, current, digital, RF, or other measurement signals from the DUT.
Remote Automated Control
Remote control is one of the most important capabilities of the RMX-4125 for automated test applications.
NI provides communication support for the RMX-412x series through:
- USB
- LAN
- RS232C
These interfaces allow automated test software to configure and control the power supply without requiring manual front-panel operation.
Constant Voltage vs Constant Current
| Feature | Constant Voltage Mode | Constant Current Mode |
|---|---|---|
| Controlled Parameter | Output Voltage | Output Current |
| Primary Regulation | Maintains Programmed Voltage | Maintains Programmed Current |
| Other Parameter | Current Depends on Load | Voltage Depends on Load |
| Typical Application | Normal DUT Power | Current-Limited Operation |
The RMX-4125 automatically operates in the appropriate CV or CC region according to the programmed voltage, programmed current, and connected load.
RMX-4125 vs RMX-4124
The RMX-4124 and RMX-4125 both provide up to 1500 W of output power, but they are optimized for different voltage and current requirements.
| Feature | RMX-4125 | RMX-4124 |
|---|---|---|
| Maximum Power | 1500 W | 1500 W |
| Maximum Voltage | 80 V | 30 V |
| Maximum Current | 56 A | 150 A |
| Rack Height | 1U | 1U |
| Best Application | Higher Voltage / Moderate Current | Lower Voltage / Very High Current |
Choose the RMX-4125 when the application requires voltage up to 80 VDC. The RMX-4124 is more appropriate when substantially higher current is required at lower voltage.
RMX-4125 vs RMX-4126
The RMX-4125 and RMX-4126 are both 1500 W programmable DC power supplies, but the RMX-4126 provides a higher maximum voltage and lower maximum current.
| Feature | RMX-4125 | RMX-4126 |
|---|---|---|
| Maximum Power | 1500 W | 1500 W |
| Maximum Voltage | 80 V | 230 V |
| Maximum Current | 56 A | 20 A |
| Rack Height | 1U | 1U |
| Best Application | Medium Voltage / Higher Current | High Voltage / Lower Current |
RMX-412x Series Comparison
| Model | Maximum Power | Maximum Voltage | Maximum Current |
|---|---|---|---|
| RMX-4124 | 1500 W | 30 V | 150 A |
| RMX-4125 | 1500 W | 80 V | 56 A |
| RMX-4126 | 1500 W | 230 V | 20 A |
| RMX-4127 | 1500 W | 650 V | 7 A |
All four models provide the same 1500 W maximum power class but target different voltage and current requirements.
AC Input Requirements
The RMX-4125 is designed for single-phase AC input power.
| AC Input Parameter | Specification |
|---|---|
| Nominal Input Rating | 100 VAC to 240 VAC |
| Nominal Frequency | 50 Hz to 60 Hz |
| Input Voltage Range | 85 VAC to 265 VAC |
| Input Frequency Range | 47 Hz to 63 Hz |
| Phase | Single Phase |
Because the RMX-4125 is a high-power 1500 W instrument, the facility power connection and circuit capacity should be verified before installation.
Important Consideration for Regenerative Loads
The RMX-4125 is a programmable DC power supply and should not be treated as a regenerative electronic load.
Applications involving regenerative loads such as certain inverters, converters, transformers, motors, or other energy-returning systems require special consideration because reverse current can affect power-supply operation.
The test-system architecture should therefore be evaluated carefully whenever the connected load can return energy toward the power supply.
Software Integration
The RMX-4125 can be integrated into computer-controlled automated test environments.
Typical software applications can use the remote interface to:
- Configure output voltage
- Configure current limits
- Control power output
- Change test conditions automatically
- Coordinate power with measurement instruments
- Execute automated validation sequences
Industries
- Automated Test Equipment
- Automotive Electronics
- Power Electronics
- Aerospace and Defense
- Industrial Electronics
- Electronic Manufacturing
- Semiconductor Test
- Research and Development
- Laboratory Testing
Applications
Automated Test Systems
The RMX-4125 provides programmable high-power DC output for automated test systems requiring software-controlled DUT power.
Power Electronics Testing
The 1500 W output capability and flexible voltage-current operating range make the RMX-4125 suitable for compatible power converters and other power electronics.
Electronic Validation
Engineers can program different voltage and current conditions to evaluate DUT behavior across its required operating range.
Production Testing
Remote programming interfaces allow the RMX-4125 to be integrated into automated manufacturing and production test stations.
Automotive Electronics Testing
The programmable DC output can provide controlled power for compatible automotive electronic modules and subsystems during validation and production testing.
Laboratory Research
Front-panel operation and remote control provide flexibility for both interactive laboratory experiments and automated research systems.
Recommended Related Products
| NI RMX-4125 | 1500 W programmable DC power supply providing up to 80 VDC and 56 A for high-power automated test applications. |
| NI RMX-4124 | 1500 W programmable DC power supply providing up to 30 V and 150 A for lower-voltage, very-high-current applications. |
| NI RMX-4126 | 1500 W programmable DC power supply providing up to 230 V and 20 A for higher-voltage applications. |
| NI RMX-4127 | 1500 W programmable DC power supply providing up to 650 V and 7 A for high-voltage, lower-current applications. |
Why Choose NI RMX-4125?
- 1500 W maximum output power
- 0 VDC to 80 VDC programmable output
- 0 A to 56 A programmable current
- Single-channel architecture
- Constant-voltage operation
- Constant-current operation
- Compact 1U rack-mount design
- Full-width rack format
- USB remote control
- LAN remote control
- RS232 remote control
- Analog control capability
- Front-panel buttons and knobs
- Calibration utility included
- Suitable for automated high-power test systems
Frequently Asked Questions
What is the NI RMX-4125?
The NI RMX-4125 is a single-channel, 1500 W programmable rack-mount DC power supply providing programmable output from 0 VDC to 80 VDC and 0 A to 56 A.
What is the part number of the RMX-4125?
The current NI ordering part number for the RMX-4125 is 784766-01.
What is the maximum output power of the RMX-4125?
The RMX-4125 provides up to 1500 W of total output power.
What is the maximum output voltage of the RMX-4125?
The RMX-4125 provides programmable output voltage up to 80 VDC.
What is the maximum output current of the RMX-4125?
The RMX-4125 provides programmable output current up to 56 A.
How many output channels does the RMX-4125 have?
The RMX-4125 is a single-channel programmable DC power supply.
Does the RMX-4125 support constant-voltage mode?
Yes. The RMX-4125 can operate in constant-voltage mode, maintaining the programmed output voltage while the current varies according to the load and configured limits.
Does the RMX-4125 support constant-current mode?
Yes. The RMX-4125 supports constant-current operation and can regulate output current according to the programmed current setting and connected load.
Can the RMX-4125 be remotely controlled?
Yes. The RMX-4125 provides USB, LAN, RS232, and analog control options for remote and automated operation.
Can the RMX-4125 be controlled over Ethernet?
Yes. The RMX-4125 includes LAN connectivity for network-based remote control and automated test integration.
Is the RMX-4125 a PXI module?
No. The RMX-4125 is a standalone 1U rack-mount programmable DC power supply rather than a PXI module. However, it can be integrated with PXI-based automated test systems through its remote communication interfaces.
How much rack space does the RMX-4125 require?
The RMX-4125 uses a 1U rack height and is designed as a full-width rack-mount instrument.
What AC input does the RMX-4125 require?
The RMX-4125 supports a nominal single-phase input of 100 VAC to 240 VAC at 50 Hz to 60 Hz. The specified AC input range is 85 VAC to 265 VAC with an input frequency range of 47 Hz to 63 Hz.
Can the RMX-4125 absorb reverse current from a regenerative load?
No. The RMX programmable power supply is not designed to sink reverse current from a regenerative load. Applications involving energy-returning loads require appropriate external system design and protection.
What is the difference between RMX-4125 and RMX-4124?
Both are 1500 W programmable DC power supplies. The RMX-4125 provides up to 80 V and 56 A, while the RMX-4124 provides up to 30 V and 150 A. The RMX-4125 is better suited to applications requiring higher voltage, while the RMX-4124 targets very-high-current applications.
What is the difference between RMX-4125 and RMX-4126?
The RMX-4125 provides up to 80 V and 56 A, while the RMX-4126 provides up to 230 V and 20 A. Both belong to the 1500 W RMX-412x power class but target different voltage and current requirements.
What applications are suitable for the RMX-4125?
Typical applications include automated test, power electronics validation, production testing, automotive electronics testing, electronic device validation, laboratory research, industrial electronics testing, and other systems requiring programmable high-power DC output.
What should I check before purchasing an RMX-4125?
Before purchasing an RMX-4125, verify the required output voltage, current and power envelope, AC input power requirements, rack installation, remote communication interface, DUT power requirements, load behavior, automation software, cabling, safety requirements, and whether the load can return energy to the power supply.
Conclusion
The NI RMX-4125 1500 W Programmable DC Power Supply combines up to 80 VDC and 56 A output capability with a compact 1U rack-mount design and USB, LAN, RS232, and analog control. Its high output power, programmable voltage and current limits, constant-voltage and constant-current operation, and remote automation capabilities make it suitable for power electronics testing, production test, automotive electronics validation, laboratory research, and high-power automated test systems.
