Q: What are the features of NI M Series devices?

A: NI M Series multifunction data acquisition (DAQ) combines analog input, analog output, digital I/O, and counter/timers on a single device. With new, innovative analog and digital designs, M Series devices set a new standard for performance, I/O capability, safety, and value. NI-MCal technology ensures accurate analog measurements at all signal ranges by compensating for nonlinearity error during self-calibration. The NI-PGIA 2 custom instrumentation class amplifier provides true 16-bit resolution at 1 MS/s scan rates and low settling times. The NI-STC 2 system timing controller implements timing and synchronization between onboard subsystems and other devices in the same system. And, with new high-speed digital isolators, industrial M Series devices offer increased accuracy and safety by removing ground loops and rejecting high common-mode voltages.

* For information about the new timing controller and NI-STC 2 refer to the analog input section.
* For information about the new calibration scheme refer to the analog input section.
* For information about the improved accuracy refer to the analog output section.

Q:What makes an M Series “multifunction”?

A: A single M Series DAQ device can provide the functionality of up to six different instruments: Digital multimeter (DMM), oscilloscope, arbitrary waveform generator, high-speed digital I/O device, and counter/timer device for frequency measurements. M Series have up to 18-bit analog inputs that provide more than 5.5 digits of resolution for DC measurements. For dynamic measurements, M Series devices can sample at 1.25 million samples per second at 16-bit resolution (1 MS/s when scanning multiple channels). Digital signals can be clocked in and out with an onboard or external clock at up to 10 MHz, eliminating the need for a dedicated high-speed digital I/O device. Correlated DIO enables digital and analog functions to be synchronized with hardware-timed precision. With up to six DMA channels (PCI/PXI) and up to 4 NI signal streaming channels (USB), all of these functions can be performed simultaneously. If a system requires additional functionality, an M Series device can be synchronized with other PCI or PXI instruments.

Q:What different M Series devices are available and what are their specifications?

A: M Series includes 5 families of devices: low-cost, high-performance, high-accuracy and industrial. All M Series devices include 32-bit counters which operate at 80 MHz. Table 1 outlines family specific information.

Family	Analog Input		Analog Output		Digital I/O	Platforms	Signal Conditioning
Family	Speed	Resolution	Speed	Resolution	Digital I/O	Platforms	Signal Conditioning
Low-Cost	Up to 250 kS/s	16-bit	833 kS/s	16-bit	1MHz, TTL, CMOS	USB, PCI, PXI	N/A
Bus-Powered	Up to 400 KS/s	16-bit	250 KS/s	16-bit	Static, TTL, CMOS	USB	N/A**
High-Speed	Up to 1.25 MS/s	16-bit (1MS/s scanning)	2.8 MS/s	16-bit	10 MHz*, TTL, CMOS	USB, PCI, PXI	N/A
High-Accuracy	Up to 625 kS/s	18-bit (500 kS/s scanning)	2.8 MS/s	18-bit	10 MHz*, TTL, CMOS	PCI, PXI	Low-pass filter
Industrial	Up to 250 kS/s	16-bit	Up to 250 kS/s	16-bit	TTL, CMOS, 24V	PCI, PXI	Isolation

Table 1. M Series Device Families

*USB devices have a maximum digital I/O rate of 1 MHz.
*Please see the analog input section for compatible signal conditioning platforms

Q: How do M Series devices compare with legacy E Series devices?

A: The following table itemizes the differences and improvements between E Series and M Series DAQ devices:

	Feature	M Series	E Series
Analog Input	Analog Input Channels	8, 16, 32, 80	16 or 64
	Sampling Rate	Up to 1.25 MS/s (16-bit)	Up to 1.25 MS/s (12-bit)
	Input Resolution	16 or 18-bit	12 or 16-bit
	Input Signal Type	Current or Voltage	Voltage
	Calibration Method	NI-MCal (all ranges)	Linear, 2-point (single range)
	Calibration Interval	1 or 2 years	1 year
	Programmable Low-pass Input Filters	Yes¹	No
Analog Output	Analog Outputs Channels	0, 2 or 4	0 or 2
	Analog Output Rate	up to 2.8 MS/s, 16-bit	up to 333 kS/s, 16-bit
	Analog Output Resolution	16-bit	12 or 16-bit
	Analog Output Ranges	Programmable per channel¹	±10 V, 0-10 V
	Analog Output Offset	Programmable per channel¹	0 V
Digital I/O	Digital I/O Lines	24 or 48	8 or 32
	Digital I/O Rate	Software timed or up to 10MHz	software-timed
	Digital Levels	TTL/CMOS or 24V²	TTL/CMOS
	Correlated DIO	Yes	No
	Digital Line Protection	Improved over/under voltage (±20 V), over current protection	-
Counter	Counter/Timers	2, 32-bit	2, 24-bit
	Counter Timebase	80 MHz	20 MHz
	Quadrature Encoder Inputs	Yes	No
	Counter Debouncing Filters	Programmable per line	None
System	Clock Synchronization	PLL, RTSI	RTSI
	DMA Channels	6³	1 or 3
	Connector Type	VHDCI (high density) or 37- pin DSUB	SCSI II
	Isolation	60 VDC continuous bank isolation, 1,400 Vrms/1,950 VDC channel-to-bus isolation, withstand for 5 seconds²	-

Table 2. Functional Differences Between M Series and E Series DAQ Devices

¹Available on High Accuracy M Series devices
² Available on Industrial M Series devices
³ M Series USB devices have Signal Streaming technology. Please see the performance section for more information on signal streaming technology.

Q: Can M Series devices be used as drop-in replacements for existing E Series devices?

A: M Series devices maintain backward compatibility with the E Series accessories and terminal blocks by retaining the same 68-pin format. The connectors on M Series devices are different than those on E Series devices, but the pin count and pin mapping are similar, so you can use M Series devices without rewiring or refixturing your existing test system. NI offers low-cost cables to directly connect M Series devices to existing terminal block and signal conditioning accessories. For applications using legacy E Series DAQ devices, an M Series device can be used with existing accessories to upgrade the speed and accuracy of the system. Cables designed for M Series devices also provide better shielding than E Series cables.

* For information about software compatibility, refer to the software section of this document.

Q: For which platforms and buses are M Series available?

A: M Series devices are available in 32-bit, 33 MHz universal PCI, PCIe, PXI, PXIe, CompactPCI , USB 1.1 and USB 2.0*. Universal PCI devices can operate in any motherboard topology:

5 V 33 MHz PCI (traditional PCI bus)
3.3 V 33 MHz PCI
3.3 V PCI 66 MHz
3.3 V PCI-X 66 MHz
3.3 V PCI-X 100 MHz
3.3 V PCI-X 133 MHz

Other DAQ devices (non-M Series) are available for PCMCIA, and IEEE 1394 (FireWire).

* USB 2.0 M Series devices will perform at slower USB 1.1 transfer rates when connected to a USB 1.1 host or hub.

Performance

Q: What is the NI-STC 2 system timing controller?

A: The NI-STC 2 is a custom-designed application-specific integrated circuit (ASIC) that controls interboard and intraboard synchronization and timing for multifunction DAQ operations. The NI-STC 2 provides

6 DMA channels – dedicated scatter-gather DMA controllers for each function
Clocked digital I/O lines (up to 10 MHz)
32-bit counter/timers with encoder compatibility
Generation and routing of the RTSI signals for multi-device synchronization
Generation and routing of internal and external timing signals
PLL for clock synchronization

Q:Why are there six DMA channels on M Series devices?

A: Many plug-in DAQ devices are limited not by their acquisition or update rates, but by the rate at which they can transfer data to PC memory. M Series devices have up to six DMA channels so a single device can perform analog input, analog output, digital input, digital output, and two counter/timer operations simultaneously while leaving the PC processor free to execute other operations. Many legacy DAQ devices have a single DMA channel, requiring two or more operations executing simultaneously to interrupt the computer processor to control the data transfer. This causes inefficiencies by blocking other operations from being processed by the PC. As data transfer rates increase and as more operations are simultaneously performed, these interrupts begin to monopolize PC processor time, causing system slowdown and eventually generating errors. M Series DAQ devices with the NI-STC 2 can execute up to six operations simultaneously at high rates while minimizing the potential for errors due to data loss or buffer overflows.

Figure 1. The NI STC 2 has six DMA channels for dramatically improved data throughput.

* This benchmark was performed with a PCI-6229 M Series device with DMA channels programmatically disabled to obtain data using 1 and 3 DMA channels. The test was performed on a 2 GHz Dell Dimension Desktop PC with Windows XP, 512 MB RAM and 30 GB hard drive.

Q: What is the RTSI bus and how does it work?

A: All plug in M Series devices include the RTSI bus, which uses a ribbon cable, or the PXI bus to route timing and trigger signals between two or more devices in the same system. With the RTSI bus, you can synchronize analog input, analog output, digital input/output, and counter/timer operations. For example, with the RTSI bus, three analog input devices can simultaneously capture data and be synchronized to a single master clock on one of the devices.

The RTSI bus is available on M Series, E Series, and other DAQ devices, in addition to IMAQ and CAN hardware.

Q: What is a phase lock loop (PLL) and how does it work?

A: With the phase lock loop (PLL) functionality available on plug-in M Series devices, you can generate an 80 MHz signal that is synchronized (phase locked) to a 10 MHz signal routed from another device. This enables multiple devices in a single system to share a master timebase while running at 80 MHz. With the PLL, PXI M Series devices can also synchronize to the PXI CLK 10 clock source.

Q:What is NI signal streaming?

A: NI signal streaming technology was created to maximize USB performance and sustain multiple bidirectional high-speed data streams. This technology also adds device-side intelligence, custom data management hardware, and streamlined data control, thereby improving single-point performance by up to 1,600 percent for analog input and up to 250 percent for analog output.

Figure 2. Single-Point Analog Input and Analog Output Performance Chart

Analog Input

Q: How is calibration performed on M Series devices?

A: Electronic components such as ADCs are characterized by nonlinearities and drift due to time and temperature. Compensating for these inherent sources of error requires device self-calibration. Legacy data acquisition devices use an onboard precision voltage reference to perform a two-point calibration for a single measurement range. This method fails to protect against localized component nonlinearities, diminishing the measurement accuracy of the device. Additionally, because this method calibrates only a single input range, measurements that scan multiple channels at varying input ranges are limited in accuracy by the tolerance of a resistor network.

M Series devices incorporate NI-MCal technology, a custom-designed linearization and calibration engine that use a highly stable reference to characterize gain, offset, and linearity errors at all ranges, providing range-specific calibration coefficients that are applied in software to provide accurate readings. The implementation of NI-MCal technology improves measurement accuracy by up to five times when compared to legacy DAQ devices. Additionally, an improved precision reference lowers the maintenance cost of the device by increasing the recommended calibration interval from one year to two years on devices in the high-speed and high-accuracy M Series families.

Q: What is the NI-PGIA 2 amplifier?

A: NI-PGIA 2 custom designed technology improves accuracy by minimizing settling time, which is a critical specification for multiplexed DAQ applications. More precisely, settling time is the amount of time required for a signal that is being amplified to reach a specified level of accuracy. If an amplifier does not have sufficient settling time, the measured signal will be digitized inaccurately. Settling time is specified by the amount of error after a given time. For any given level of resolution (or accuracy), shorter settling times are desired because they allow faster sampling rates without sacrificing accuracy. Off-the-shelf programmable gain instrumentation amplifiers (PGIAs) are not optimized for scanning multiple channels at varying voltage levels on a single device.

The following chart shows the settling time error of the high speed NI-PGIA 2 compared to a legacy NI-PGIA, and an off-the-shelf PGIA following a 20 V step.

Figure 3. NI-PGIA 2 technology provides faster settling times than legacy and off-the-shelf PGIA technologies.

Q: What is temperature-drift?

A: The accuracy of your DAQ device changes with the temperature of the device. M Series devices use several technologies to minimize error due to temperature drift, including the following:

An onboard temperature sensor readable through software to monitor changing device temperatures
Components with consistent values over a wide temperature range
Compensating components that correct for error

Q:What are programmable low-pass filters and how do they work?

A: A low-pass filter attenuates signals with frequencies above the cut-off frequency while passing signals below the cut-off frequency. The cut-off frequency is defined as the frequency at which the output amplitude has decreased by 3 dB. Low-pass filters attenuate noise and reduce aliasing of signals beyond the Nyquist frequency (defined as ½ the sampling frequency).

Generally, analog input signals measured with plug-in DAQ devices require external signal conditioning to filter high-frequency noise. High Accuracy M Series devices have an onboard programmable filter, eliminating the need for external hardware to provide this filtering capability. This low-pass filter can be programmatically engaged or disengaged with a cutoff frequency of 40 kHz.

Q:What is isolation?

A: Isolation electrically and physically separates sensor signals, which can be exposed to high voltage transients and noise,from the measurement system’s low-voltage backplane. Isolation offers many benefits including:

Protection for expensive equipment, the user, and data from transient voltages
Improved noise immunity
Ground loop removal
Increased common-mode voltage rejection

Isolated measurement devices provide separate ground planes for the analog and/or digital front end(s) and the device backplane to separate the sensor measurements from the rest of the system. The ground connection of the isolated front end is a floating pin that can operate at a different potential from the earth ground. Any common-mode voltage that exists between the ground and the measurement system ground is rejected (within the devices working voltage specification). Isolation also prevents ground loops from forming, helping reduce noise in the measurement signals.

Figure 4. Bank Isolated Analog Input Circuitry

Industrial M Seriesdata acquisition devices use Analog Devices iCoupler digital isolators to provide 60 VDC continuous isolation and 1,400 Vrms/1,900 VDC channel-to-bus isolation withstand for 5 s on multiple analog and digital channels and support sampling rates up to 250 kS/s.

For more information on isolation, please refer to Isolation Technologies for Reliable Industrial Measurements.

Q:What signal conditioning devices are compatible with M Series devices for sensor measurements?

A: All plug-in M Series devices work with both SCC and SCXI signal conditioning. 68-pin USB M Series devices also works with SCC signal conditioning. Both SCC and SCXI improve measurement accuracy by providing additional amplification of low-level sensor signals and with low-pass filters to eliminate noise sources, including 50/60 Hz noise from power lines. Additionally, SCC and SCXI provide sensor-specific signal conditioning such as CJC for thermocouples, and provide excitation power for sensors such as strain gages and RTDs.

Analog Output

Q: How do multiple analog output ranges improve accuracy?

A: Multifunction DAQ devices have traditionally offered two analog output ranges, either bipolar (±10 V) or unipolar (0 to 10 V). With this limitation, the bits of resolution of the digital-to-analog converter (DAC) are distributed equally across the entire range. For a 16-bit DAC with 65,536 codes of resolution (2¹⁶), the minimum output step for a ±10 V range is 305 µV (20 V 65,536). It is impossible for the DAC to output voltage changes smaller than 305 µV.

High Accuracy M Series DAQ devices feature programmable output ranges that distribute the number of bits over a much smaller voltage range. For example, with a ±1 V range and 16-bit DAC resolution, the device can output 31 µV changes.

Q: What are programmable DC offsets for analog outputs?

A: Some applications require small changes in analog output level around a fixed DC offset. For example, to model 5 V power supply noise requires analog outputs that can simulate a small amount of noise (submillivolts) on a 5 VDC signal. With a traditional multifunction DAQ device that has a single output range without offsets, the range would have to be set at 0 to 10 V. Even with 16-bit resolution, the digital-to-analog converter (DAC) could only represent 153 µV changes.

High Accuracy M Series devices have programmable analog output offsets which enable much finer resolution around a specified offset value. When used in conjunction with the programmable range feature, the programmable offset enables an M Series board to model 5 V power supply noise by using all 16-bits of resolution on a 4 to 6 V range (5 V offset with a ±1 V range). This improves the minimum code width to 31 µV.

Digital I/O and Counter/Timers

Q: What is correlated digital I/O and how does it work?

A: Correlated I/O enables synchronization of onboard digital I/O lines to a clock reference.

Internal or External Clocks

Multiple digital lines on the same device can be synchronized to a common clock which enables multibit pattern detection. It also enables clocked digital waveform generation or acquisition at rates up to 10 MHz.

Analog I/O and counter/timers

M Series enables you to time-correlate different operations with analog I/O, digital I/O and counter/timers. For example, you can synchronize digital and analog samples in time by sharing your AI clock as the source of your digital I/O clock. To sample a digital signal independent of an AI, AO, or DO operation, you can configure a counter to generate the desired DI clock or use an external signal as the source of the clock.

Q: What is industrial digital I/O?

A:Industrial applications often involve requirements beyond the capabilities of a typical measurement device. For example, many industrial sensors and actuators require 24 V logic levels and may operate at different voltage potentials that can cause ground loops. Safety for the measurement or control system and safety for the user or operator are equally important. With voltage levels up to 30 V, high current drive, and isolation, NI M Series devices can connect directly to a wide array of industrial pumps, valves, motors, and other sensors/actuators while providing a high degree of safety and reliability.

Q: What are programmable power-up states?

A: When a computer is powered on, various components begin their own power-up routines to ensure that they reach a functional and expected state. If digital outputs are used inside the computer to control machinery or an industrial process, it is important that the digital outputs are also initialized to a known state. Changing the outputs typically requires that an application is running, but the module may be on for several minutes before the application can start.

Using programmable power-up states, you can configure the initial digital output states in software to ensure glitch-free operation when connected to industrial actuators such as pumps, valves, motors, and relays. An Industrial M Series device holds these output states after receiving power, so your computer can boot and your software application can begin running. Programmable power-up states are glitch-free, meaning the outputs never go through an incorrect state during power up. You can configure each individual digital line as high-output or low output. Each Industrial M Series device stores the settings in onboard non volatile memory and implements the power-up states instantaneously after power is applied to the device.

Q: What is the difference between software-timed and hardware-timed digital I/O?

A: Software-timed digital I/O is system dependent, and speeds vary based on the processing power of the host PC. This is also referred to as “static” DIO. Clocked digital I/O is hardware-timed, meaning the update or sampling rate is governed by a stable clock source. This clock is independent of the system used. M Series devices can use an onboard clock source or an external signal as the digital timebase.

Q: What is the benefit of an onboard 80 MHz clock?

A: The 80 MHz timebase can be used as the source input to the 32-bit general-purpose counter/timers. It improves the accuracy of frequency measurements and generation versus the 20 MHz timebase on E Series DAQ devices. A faster timebase improves pulse width and period measurement accuracy and enables faster pulse train signal generation.

Figure 5. Single Point Frequency Measurement

Q: How do 32-bit counters compare to lower resolution counters?

A: A counter is specified by the number of events it can count before resetting. For example, a 32-bit counter can count 2³², or over 4 billion events. This is over 65 thousand times more register capacity than the 16-bit counter/timers found on other DAQ devices. If a counter/timer exceeds its maximum count capacity during an operation, the register resets and data is lost.

Q: Why is filtering important on counter/timer input lines?

A: In process control applications involving frequency sensors and in relay monitoring applications, the sensors often exhibit bouncing, especially if a mechanical relay drives the output of the sensor. With input filters enabled on the counter/timer lines on M Series device, it samples the input on each rising edge of a filter clock. When the filter clock has sampled the signal high on N consecutive edges, the low to high transition is propagated to the rest of the circuit. The value of N depends on the filter setting. In Figure 6, the value of N is set to 5.

Figure 6. Filtered Counter/Timer Line

Software

Q: What driver software is provided with M Series devices?

A: Many DAQ devices come with just a basic DAQ device driver. Some devices require the separate purchase of driver software even for basic functionality. All M Series devices include NI-DAQmx measurement services and driver software.

NI-DAQmx measurement services software controls every aspect of your DAQ system: configuration, programming, and low-level operating system device control. With NI-DAQmx software, you can quickly configure and acquire measurements. NI-DAQmx features virtual channels that automatically scale raw data into engineering units. NI-DAQmx also features the DAQ Assistant, a utility that configures DAQ applications with zero programming and automatically generates code.

NI-DAQmx software goes far beyond a basic DAQ driver to deliver increased productivity and performance. Consider the following software criteria when you purchase your DAQ system.

	Measurement Services Features	NI-DAQmx Measurement Services	Basic DAQ Driver
Productivity	Automatic code generation	*	—
	Configuration management	*	—
	Analog, digital, and counter test panels	*	o
	Scaling to real-world units	*	—
	Single API for all hardware and I/O types	*	—
	Measurement examples	>3000	<20
	Pin-point error diagnostics	*	—
Performance	Optimized multithreaded I/O performance	*	—
	Optimized single-point loops	*	o
	Real-time capabilities	*	—
	Advanced calibration	*	—

Table 3. Comparison Between NI-DAQmx and Basic DAQ Driver Software

Key: * Best o Good — Not Provided

For more information on the DAQmx driver, please see Transition from Traditional NI-DAQ to NI-DAQmx in LabVIEW

Q:What operating systems work with M Series?

A: Use the NI Hardware and Software Operating System Compatibility page to select the M Series device of choice and see which operating systems are compatible. For older operating systems, it may be necessary to download the full table as directed on the page.

Q:Which application development environments work with M Series?

A: M Series DAQ devices work with every development environment compatible with NI-DAQmx, including:

LabVIEW 7.x or later
LabVIEW Real-Time 7.1 or later*
LabVIEW SignalExpress LE or higher
LabWindows/CVI 7.x or later
Measurement Studio 7.x or later
ANSI C/C++
C#
Visual Basic .NET
Visual Basic 6.0

*Not compatible with USB devices

Q:Do I need to make changes to my code if I replace an E Series device with an M Series device?

A: Existing NI-DAQmx applications written for an E Series device run unchanged on an M Series device. You may need to perform additional programming to take advantage of the advanced timing and synchronization features of M Series.

Q: Which real-time tools work with M Series?

A: All PCI and PXI M Series devices can be used with LabVIEW Real-Time and NI-DAQmx to build reliable, deterministic, stand-alone applications with no user interaction required. The NI-DAQmx API is optimized for easier implementation and faster development of real-time applications than traditional real-time operating systems.

USB M Series devices are not compatible with LabVIEW Real-Time.

Service and Support

Q:How do I get technical support for M Series devices?

A: NI offers extensive support options through www.ni.com/support. You can call, e-mail, or troubleshoot problems online with NI engineers. In addition, ni.com provides a wealth of resources for customers--from user getting started with M Series to DAQ experts looking for tips from the designers. Online resources include:

Downloadable drivers and updates for NI-DAQmx and other measurement products
Over 3,000 KnowledgeBase entries
Online product manuals (downloadable help files and PDFs)
Over 3,000 example programs
Tutorials and application notes

Q:What training is available for M Series devices?

A: The concepts of DAQ are taught in regional seminars and customer education courses. You can get a free hands-on tutorial through one of our regularly scheduled training seminars, offered by your local field engineer. To find a free seminar in your area, visit www.ni.com/events.

NI also offers a 3-day DAQ course that covers the theory of DAQ and includes hands-on work with multifunction DAQ, signal conditioning, and NI-DAQmx software. To learn more or to enroll in a course, visit ni.com/training.

Q:What options are available for OEM customers?

A: In addition to supplying free 7-day evaluation kits and world-class technical support, NI offers pricing discounts for qualified OEM applications. Several devices are designed for use in such applications. M Series leads the market in MIO channel density, lowering your cost and space requirements. M Series devices offer up to 80 analog input, 4 analog output, and 48 digital I/O lines. In addition, 32-bit counter/timers can generate or measuring long pulses without the need to cascade multiple channels. With NI-DAQmx software you can quickly implement and test your design iterations, greatly reducing your development time and cost.

For more information on hardware and software customization, contact us.

Q:What warranty is provided with M Series devices?

A: All M Series devices have a 1-year warranty that covers against defects in workmanship and material from the date of shipment of the product. Extended warranty options are available that can help you to fix your maintenance costs over 2 or more years. Contact your NI sales representative for more information.

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