NI-9215 C Series 16 Bit Voltage AI Module

It employs a 16-bit SAR (Successive Approximation Register) ADC, supporting ±10 V input range and 100 kS/s/ch synchronous sampling. This module achieves true synchronous sampling through independent track/hold amplifiers for each channel, features dual channel-to-ground isolation barriers (bolt/spring terminal version 250 Vrms CAT II, ​​BNC version 60 VDC CAT I), and NIST traceable calibration, making it excellent for industrial measurement, structural monitoring, and engine combustion analysis. The module offers three connection methods—bolt terminals, spring terminals, and BNC.It is a cost-effective choice for medium-speed, high-precision voltage measurement needs.

The NI-9215 C Series 16 Bit Voltage AI Module is positioned in the "synchronous sampling + medium speed" range within the C-series voltage input module product line, filling the gap between low-speed, high-precision (e.g., NI-9209, 24-bit 500 S/s) and high-speed, medium-precision (e.g., NI-9222, 16-bit 500 kS/s/ch) modules. Its 73 dB CMRR and 1 GΩ input impedance ensure signal integrity in noisy industrial environments, and its 1,167,174-hour MTBF demonstrates its long-term reliability. It's important to note that this module only supports differential input (4 channels differential, 0 channels single-ended) and does not support single-ended input mode.

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Description

The NI-9215 is a high-precision voltage input module in NI's C series modular I/O platform, designed for applications requiring simultaneous acquisition of multiple voltage signals. Its core feature is four differential analog input channels, each equipped with an independent 16-bit SAR ADC and a track/hold amplifier, ensuring all channels can sample simultaneously and eliminating inter-channel phase deviation caused by multiplexer switching. The module has an input range of ±10 V (not software switchable), a maximum sampling rate of 100 kS/s/ch, and provides ±30 V overvoltage protection to handle unexpected voltage surges.

The most significant design highlight of the NI-9215 C Series 16 Bit Voltage AI Module is its dual isolation barrier to ground. The bolt-terminal and spring-terminal versions offer 250 Vrms continuous isolation (Measurement Category II) and a withstand voltage of 2,300 Vrms, while the BNC version offers 60 VDC continuous isolation (Measurement Category I) and a withstand voltage of 1,500 Vrms. This isolation design not only protects the measurement system from high-voltage damage but also ensures signal integrity by eliminating ground loops and improving common-mode rejection.

In terms of product line positioning, the NI-9215 differs from the asynchronously sampled NI-9201 (12-bit, 500 kS/s, 8-channel single-ended) and NI-9205 (16-bit, 250 kS/s, 32-channel), and also from the higher sampling rate NI-9222 (16-bit, 500 kS/s/ch) and NI-9223 (16-bit, 1 MS/s/ch). Its 100 kS/s/ch sampling rate perfectly covers applications requiring mid-frequency band, high precision, and synchronous acquisition, such as vibration analysis, structural monitoring, and engine combustion pressure measurement.

Features

• Synchronous sampling architecture

The NI-9215's independent ADC + track/hold amplifier architecture for each channel allows all four channels to be sampled on the same clock edge. Compared to multiplexed modules (such as the NI-9205), the core advantages of synchronous sampling are:

Zero inter-channel phase skew: The sampling time difference between all channels is zero, suitable for applications requiring precise inter-channel timing relationships (such as three-phase power measurement and multi-axis vibration analysis).

No need for inter-channel interpolation compensation: Multiplexer modules have a fixed inter-channel delay during high-speed sampling, requiring software compensation; the NI-9215 completely eliminates this problem.

Predictable conversion time: The total conversion time is 10 μs when all four channels are operating simultaneously, and only 4.4 μs when operating a single channel

• Dual isolation between the passage and the ground

The triple benefits of isolation barriers: safety protection (preventing high voltage from entering the low-voltage side), noise immunity (breaking ground loops, 73 dB CMRR), and high common-mode voltage range (allowing the COM terminal to float).

Positioning of NI-9215 in C-Series Voltage Input Modules

The NI-9215 C Series 16 Bit Voltage AI Module's unique value proposition lies in its status as an entry-level option in the C-Series product line for simultaneous sampling and BNC connectivity. It is the optimal choice when applications require BNC connectors (such as in laboratory environments) and simultaneous sampling, but do not need the NI-9222's 500 kS/s/ch or the NI-9223's 1 MS/s/ch.

The NI-9215 supports only differential input mode, providing two input terminals, AI+ and AI-, per channel. The advantages of differential measurement include:

• Common-mode rejection: 73 dB (60 Hz) CMRR effectively suppresses power line noise and common-mode interference
• High input impedance: 1 GΩ (AI-to-COM) for the screw/spring terminal version, 200 kΩ (AI-to-COM) for the BNC version, resulting in minimal load on the signal source
• Floating ground signal connection: For floating ground differential signals, it is recommended to connect AI- to COM via a 1 MΩ resistor to keep the common-mode voltage within the specified range

The NI-9215 supports the following connection topologies:

• Grounded Differential Connection: When the signal source has a reference ground, connect AI+ to the positive terminal, AI- to the negative terminal, and COM to the signal source ground. This is the most common industrial measurement connection method
• Floating Ground Differential Connection: When the signal source has no reference ground (such as a battery-powered sensor), a 1 MΩ resistor needs to be connected between AI- and COM to provide a common-mode bias path. Note that this circuit is integrated in the BNC version
• Single-Ended Connection (Differential Mode Implementation): Although the module does not support native single-ended mode, the positive terminal of the signal can be connected to AI+, the ground terminal to AI-, and AI- connected to COM to achieve an equivalent single-ended measurement in a differential manner. In this case, attention should be paid to the common-mode voltage range constraints.

Overvoltage Protection:

Each channel provides ±30 V overvoltage protection, effective regardless of whether the module is powered on or off. This means that at the ±10 V range, accidental overvoltages up to 3 times full scale are permissible without damaging the module.

Sleep Mode:

The NI-9215 C Series 16 Bit Voltage AI Module supports a low-power sleep mode with a power consumption of only 25 μW, suitable for battery-powered or long-term unattended data logging applications. In active mode, the maximum power consumption is 560 mW (powered from the chassis at full-scale input and 100 kS/s sampling).

High Vibration Environment Connection Protection, For high vibration applications, NI recommends:

• Using ferrules to terminate the leads to the detachable connector
• Using the NI-9927 back shell connector kit for bolt terminal blocks
• Using the NI-9981 back shell connector kit for spring terminal blocks

Physical Properties

Key NI-DAQmx features working with the NI-9215:

• DAQ Assistant: An interactive configuration tool that allows you to create acquisition tasks without programming
• MAX (Measurement & Automation Explorer): Hardware discovery, self-test, configuration, and calibration management
• Hardware-Timed Single Point: Supports deterministic control loops up to 5 kHz on CompactRIO
• Multi-rate acquisition: CompactDAQ's three AI timing engines allow simultaneous acquisition at different sampling rates

Customization

We get it that standard arrangements do not continuously meet one of a kind prerequisites. Our experienced building group gives comprehensive OEM/ODM customization administrations. Whether you require adjusted recurrence ranges, specialized activating alternatives, or custom frame components, we work closely with you to create the idealize arrangement. Our adaptable plan approach guarantees your particular application needs are completely tended to whereas keeping up our quality standards.

Cases:

FAQs:

✅The NI-9215 is available in screw, spring, and BNC connector versions. Are their internal electrical structures the same?

A: 

Not entirely the same, which directly affects the test results of floating signals.

• Screw/Spring Terminal Version: Extremely high input impedance (1GΩ). If connected to a floating signal source (such as a battery or an ungrounded isolated sensor), the lack of a charge discharge circuit can easily cause the channel common-mode voltage to exceed the limit, resulting in reading drift, lockout, or saturation. A bias resistor of approximately 1 M ohm must be connected in parallel between the physical negative terminal (AI-) and the module's common ground terminal (COM) to provide a ground reference.

• BNC Connector Version: It integrates a dedicated bias conditioning circuit. Simply plugging in a BNC cable automatically maintains common-mode balance, eliminating the need for a manual external bias resistor.

✅The module is rated for 250 Vrms isolation, so why did it still burn out the computer or circuit board when testing an external 24V ground potential difference signal?

A:

• Channel-to-Earth Isolation: The NI-9215 features hardware-level dual isolation barriers, allowing a voltage difference of up to 250 Vrms (screw terminal version) or 60 VDC (BNC version) between all four channels and the external chassis/computer ground.
• No Channel-to-Channel Isolation: Although the module as a whole is isolated from the outside, the internal reference grounds (outer ring shielding of COM or BNC) of these four channels are interconnected. If you attempt to test ground A of one system using channel 1 and ground B of another system using channel 2, and there is a large voltage difference between ground A and ground B, this will cause a large current to short-circuit directly through the module's internal common ground, instantly burning out the module. For testing multiple different ground sources, a module with "complete channel-to-channel isolation" (such as the NI-9225/9229) must be selected.

✅Can I unplug it and hot-swappable it to another running cDAQ chassis?

A:

Hot-swapping is supported, but software response needs to be considered. The NI-9215 belongs to the C-series modules, and its hardware fully supports hot-swapping. If you insert the module while the system is powered on, the cDAQ chassis will automatically enumerate and recognize the card via the chip bus. However, please note: if your LabVIEW test software is running, a sudden hot-swapping will cause the executing DAQmx task to momentarily crash and throw a fatal "Module disconnected" error code. The hardware is harmless, but the software needs to be prepared for error prevention or system shutdown.

Contact Us

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Contact our technical specialists at manager03@mxtdinfo.com  / manager02@mxtdinfo.com for detailed specifications, pricing information, or to discuss your custom requirements. We're committed to delivering the perfect NI-9215 C Series 16 Bit Voltage AI Module solution for your application needs.