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NI 6236 User Manual

Isolated current input/voltage output devices
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  • Page 1 PCI-6236...
  • Page 2 DAQ M Series NI 6236 User Manual Isolated Current Input/Voltage Output Devices NI 6236 User Manual May 2006 371948A-01...
  • Page 3 Support Worldwide Technical Support and Product Information ni.com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin, Texas 78759-3504 USA Tel: 512 683 0100 Worldwide Offices Australia 1800 300 800, Austria 43 0 662 45 79 90 0, Belgium 32 0 2 757 00 20, Brazil 55 11 3262 3599,...
  • Page 4 Warranty The NI 6236 is warranted against defects in materials and workmanship for a period of three years from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period.

  • Page 5: Table Of Contents

    LabVIEW ......................xv ™ ™ LabWindows /CVI ..................xvi Measurement Studio..................xvi ANSI C without NI Application Software ............xvi .NET Languages without NI Application Software ........xvi Device Documentation and Specifications............xvii Training Courses .....................xvii Technical Support on the Web ................xvii Chapter 1 Getting Started Installing NI-DAQmx ....................1-1...
  • Page 6 Using a Digital Source..............4-21 Routing AI Start Trigger to an Output Terminal ......4-21 AI Reference Trigger Signal ................4-22 Using a Digital Source..............4-23 Routing AI Reference Trigger Signal to an Output Terminal ..4-23 NI 6236 User Manual ni.com...
  • Page 7 Getting Started with AO Applications in Software ............5-11 Chapter 6 Digital Input and Output I/O Protection.........................6-1 Programmable Power-Up States ..................6-2 Connecting Digital I/O Signals..................6-2 Getting Started with DIO Applications in Software ............6-3 © National Instruments Corporation NI 6236 User Manual...
  • Page 8 Retriggerable Single Pulse Generation..........7-21 Pulse Train Generation..................7-22 Continuous Pulse Train Generation..........7-22 Frequency Generation ..................7-23 Using the Frequency Generator ............7-23 Frequency Division ..................7-24 Pulse Generation for ETS ................7-24 NI 6236 User Manual viii ni.com...
  • Page 9 Example Application That Works Incorrectly (Duplicate Counting)..............7-35 Example Application That Prevents Duplicate Count ......7-35 When To Use Duplicate Count Prevention........7-36 Enabling Duplicate Count Prevention in NI-DAQmx ......7-37 Synchronization Modes ...................7-37 80 MHz Source Mode ...............7-38 Other Internal Source Mode..............7-38 External Source Mode...............7-38 ©...
  • Page 10 Using RTSI as Outputs ................... 10-5 Using RTSI Terminals as Timing Input Signals..........10-6 RTSI Filters..................... 10-6 PXI Clock and Trigger Signals..................10-8 PXI_CLK10 ....................10-8 PXI Triggers....................10-8 PXI_STAR Trigger ..................10-8 PXI_STAR Filters................... 10-9 NI 6236 User Manual ni.com...
  • Page 11 Chapter 12 Triggering Triggering with a Digital Source ...................12-1 Appendix A NI 6236 Device Information NI 6236 Pinout.......................A-1 NI 6236 Specifications....................A-3 NI 6236 Accessory and Cabling Options ..............A-3 Appendix B Troubleshooting Analog Input ........................B-1 Analog Output........................B-2 Counters .........................B-3 Appendix C...

  • Page 12: About This Manual

    About This Manual The NI 6236 User Manual contains information about using the NI 6236 M Series data acquisition (DAQ) devices with NI-DAQ 8.1 and later. National Instruments 6236 devices feature four analog current input (AI) channels, four analog voltage output (AO) channels, two counters, six lines of digital input (DI), and four lines of digital output (DO).

  • Page 13: Related Documentation

    Each application software package and driver includes information about writing applications for taking measurements and controlling measurement devices. The following references to documents assume you have NI-DAQ 8.1 or later, and where applicable, version 7.0 or later of the NI application software. NI-DAQ...

  • Page 14: Ni-Daqmx Base

    About This Manual NI-DAQmx Base The NI-DAQmx Base Getting Started Guide describes how to install your NI-DAQmx Base software, your NI-DAQmx Base-supported DAQ device, and how to confirm that your device is operating properly. Select Start»All Programs»National Instruments»NI-DAQmx Base»Documentation» Getting Started Guide.

  • Page 15: Labwindows ™ /Cvi

    Studio NI-DAQmx .NET and Visual C++ class libraries. This help collection is integrated into the Microsoft Visual Studio .NET documentation. In Visual Studio .NET, select Help»Contents. Note You must have Visual Studio .NET installed to view the NI Measurement Studio Help. ANSI C without NI Application Software The NI-DAQmx Help contains API overviews and general information about measurement concepts.

  • Page 16: Device Documentation And Specifications

    All Programs»National Instruments»NI-DAQ»Browse Device Documentation. Training Courses If you need more help getting started developing an application with NI products, NI offers training courses. To enroll in a course or obtain a detailed course outline, refer to ni.com/training Technical Support on the Web For additional support, refer to ni.com/support...

  • Page 17: Getting Started

    (AO) channels, two counters, six lines of digital input (DI), and four lines of digital output (DO). If you have not already installed your device, refer to the DAQ Getting Started Guide. For NI 6236 device specifications, refer to the NI 6236 Specifications on ni.com/manuals...

  • Page 18: Device Specifications

    Document Browser or , for more detailed information ni.com/manuals about NI 6236 devices. Device Accessories and Cables NI offers a variety of accessories and cables to use with your DAQ device. Refer to Appendix A, NI 6236 Device Information, or for more ni.com...

  • Page 19: Daq System Overview

    Figure 2-1. Components of a Typical DAQ System DAQ Hardware DAQ hardware digitizes input signals, performs D/A conversions to generate analog output signals, and measures and controls digital I/O signals. Figure 2-2 features the components of NI 6236 devices. © National Instruments Corporation NI 6236 User Manual...

  • Page 20: Daq-Stc2

    PFI/Static DO Figure 2-2. General NI 6236 Block Diagram DAQ-STC2 The DAQ-STC2 implements a high-performance digital engine for NI 6236 data acquisition hardware. Some key features of this engine include the following: • Flexible AI and AO sample and convert timing •...

  • Page 21: Calibration Circuitry

    To return a device to its initial factory calibration settings, software can copy the factory-calibration constants to the user-modifiable section of the EEPROM. Refer to the NI-DAQmx Help or the LabVIEW 8.x Help for more information about using calibration constants.

  • Page 22: Cables And Accessories

    Chapter 2 DAQ System Overview Cables and Accessories NI offers a variety of products to use with NI 6236 devices, including cables, connector blocks, and other accessories, as follows: • Cables and cable assemblies – Shielded – Unshielded ribbon •...

  • Page 23: Programming Devices In Software

    VIs you can call from your application software, such as LabVIEW or LabWindows/CVI, to program all the features of your NI measurement devices. Driver software has an application programming interface (API), which is a library of VIs, functions, classes, attributes, and properties for creating applications for your device.

  • Page 24: Connector Information

    AO <0..3> AO GND Output Analog Output Channels 0 to 3—These terminals supply the voltage output of AO channels 0 to 3. Note: AO <0..3> are isolated from earth ground and chassis ground. © National Instruments Corporation NI 6236 User Manual...

  • Page 25: Rtsi Connector Pinout

    External Calibration Negative Reference—CAL– supplies the negative reference during external calibration of the NI 6236. RTSI Connector Pinout Refer to the RTSI Connector Pinout section of Chapter 10, Digital Routing Generation, for information about the RTSI connector. and Clock NI 6236 User Manual ni.com...

  • Page 26: Analog Input

    The NI programmable gain instrumentation amplifier (PGIA) is a measurement and instrument class amplifier that minimizes settling times for all input ranges. The NI-PGIA can amplify or attenuate an AI signal to ensure that you use the maximum resolution of the ADC.

  • Page 27: Analog Input Range

    Chapter 4 Analog Input M Series devices use the NI-PGIA to deliver high accuracy even when sampling multiple channels with small input ranges at fast rates. M Series devices can sample channels in any order at the maximum conversion rate, and you can individually program each channel in a sample with a different input range.

  • Page 28: Connecting Analog Current Input Signals

    5% over what the previous formulas would indicate. Table 4-1 shows the input range and resolution supported by the NI 6236 devices. Table 4-1. Input Ranges for NI 6236...

  • Page 29: Method 2

    Method 2, shown in Figure 4-3, ties the AI – input to AI GND. When measuring current up to 20 mA, this type of connection ensures that the voltage level on both the positive and negative side are within the common-mode input range for NI 6236 devices. Isolation Barrier AI + AI –...

  • Page 30: Analog Input Ground-Reference Settings

    AI GND is the ground-reference point that NI 6236 devices use to reference their isolated front end. The NI 6236 is an isolated device with isolation ratings up to 60 VDC/30 Vrms. This allows for current measurement at high voltage levels provided that the common-mode input range requirement is satisfied.
  • Page 31 Analog input ground-reference setting refers to the reference that the PGIA measures against. Differential is the only ground-reference setting for NI 6236 analog input signals, which means that the PGIA always measures the voltages between AI + and AI – generated across the input sense resistor, regardless of which analog input connection method is used.

  • Page 32: Configuring Ai Ground-Reference Settings In Software

    Exceeding the maximum input voltage or maximum working voltage rating also can damage the device and the computer. Exceeding the maximum input voltage can cause injury and harm the user. NI is not liable for any damage or injuries resulting from such signal connections.

  • Page 33: Multichannel Scanning Considerations

    The NI-PGIA then amplifies the input signal with the gain for the new input range. Settling time refers to the time it takes the NI-PGIA to amplify the input signal to the desired accuracy before it is sampled by the ADC.

  • Page 34: Avoid Scanning Faster Than Necessary

    1, and so on. You also could read all 100 points from channel 0 then read 100 points from channel 1. The second method switches between channels much less often and is affected much less by settling time. © National Instruments Corporation NI 6236 User Manual...

  • Page 35: Analog Input Data Acquisition Methods

    With a software-timed acquisition, software controls the rate of the acquisition. Software sends a separate command to the hardware to initiate each ADC conversion. In NI-DAQmx, software-timed acquisitions are referred to as having on-demand timing. Software-timed acquisitions are also referred to as immediate or static acquisitions and are typically used for reading a single sample of data.

  • Page 36: Non-Buffered

    Signal, and AI Pause Trigger Signal sections for information about these triggers. A digital trigger can initiate these actions. NI 6236 devices support digital triggering, but do not support analog triggering. Field Wiring Considerations Environmental noise can seriously affect the measurement accuracy of the device if you do not take proper care when running signal wires between signal sources and the device.

  • Page 37: Analog Input Timing Signals

    This kind of connection is required for signals traveling through areas with large magnetic fields or high electromagnetic interference. Refer to the NI Developer Zone document, Field Wiring and Noise Considerations for Analog Signals, for more information. To access this...
  • Page 38 The sample counter is loaded with the specified number of posttrigger samples, in this example, five. The value decrements with each pulse on ai/SampleClock, until the value reaches zero and all desired samples have been acquired. © National Instruments Corporation 4-13 NI 6236 User Manual...
  • Page 39 If an ai/ReferenceTrigger pulse occurs before the specified number of pretrigger samples are acquired, the trigger pulse is ignored. Otherwise, when the ai/ReferenceTrigger pulse occurs, the sample counter value decrements until the specified number of posttrigger samples have been acquired. NI 6236 User Manual 4-14 ni.com...

  • Page 40: Ai Sample Clock Signal

    A programmable internal counter divides down the sample clock timebase. Several other internal signals can be routed to ai/SampleClock through RTSI. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information. Using an External Source Use one of the following external signals as the source of ai/SampleClock: •...

  • Page 41: Routing Ai Sample Clock Signal To An Output Terminal

    Chapter 4 Analog Input Note Refer to the NI 6236 Specifications for the minimum allowable pulse width and the propagation delay of PFI <0..5>. Routing AI Sample Clock Signal to an Output Terminal You can route ai/SampleClock out to any output PFI <6..9> or RTSI <0..7>...

  • Page 42: Ai Sample Clock Timebase Signal

    You can specify either an internal or external signal as the source of ai/ConvertClock. You also can specify whether the measurement sample begins on the rising edge or falling edge of ai/ConvertClock. © National Instruments Corporation 4-17 NI 6236 User Manual...

  • Page 43: Using An Internal Source

    • RTSI <0..7> • PXI_STAR Note Refer to the NI 6236 Specifications for the minimum allowable pulse width and the propagation delay of PFI <0..5>. Routing AI Convert Clock Signal to an Output Terminal You can route ai/ConvertClock (as an active low signal) out to any output PFI <6..9>...

  • Page 44: Using A Delay From Sample Clock To Convert Clock

    Figure 4-13 shows timing sequences for a four-channel acquisition (using AI channels 0, 1, 2, and 3) and demonstrates proper and improper sequencing of ai/SampleClock and ai/ConvertClock. © National Instruments Corporation 4-19 NI 6236 User Manual...

  • Page 45: Ai Convert Clock Timebase Signal

    The polarity of ai/HoldCompleteEvent is software-selectable, but is typically configured so that a low-to-high leading edge can clock external AI multiplexers indicating when the input signal has been sampled and can be removed. NI 6236 User Manual 4-20 ni.com...

  • Page 46: Ai Start Trigger Signal

    Counter n Internal Output • PXI_STAR Note Refer to the NI 6236 Specifications for the minimum allowable pulse width and the propagation delay of PFI <0..5>. The source also can be one of several other internal signals on your DAQ device.

  • Page 47: Ai Reference Trigger Signal

    Figure 4-14 shows the final buffer. Reference Trigger Pretrigger Samples Posttrigger Samples Complete Buffer Figure 4-14. Reference Trigger Final Buffer NI 6236 User Manual 4-22 ni.com...

  • Page 48: Using A Digital Source

    RTSI <0..7> • PXI_STAR Note Refer to the NI 6236 Specifications for the minimum allowable pulse width and the propagation delay of PFI <0..5>. The source also can be one of several other internal signals on your DAQ device. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information.

  • Page 49: Routing Ai Pause Trigger Signal To An Output Terminal

    I/O data transfer mechanisms. Some of the applications also use start, reference, and pause triggers. Note For more information about programming analog input applications and triggers in software, refer to the NI-DAQmx Help or the LabVIEW 8.x Help. NI 6236 User Manual 4-24...

  • Page 50: Analog Output

    Analog Output NI 6236 devices have four AO channels that are controlled by a single clock and are capable of waveform generation. Figure 5-1 shows the analog output circuitry of NI 6236 devices. Isolation Barrier DAC0 AO 0 AO 1...

  • Page 51: Minimizing Glitches On The Output Signal

    With a software-timed generation, software controls the rate at which data is generated. Software sends a separate command to the hardware to initiate each DAC conversion. In NI-DAQmx, software-timed generations are referred to as on-demand timing. Software-timed generations are also referred to as immediate or static operations.

  • Page 52: Hardware-Timed Generations

    There are several different methods of continuous generation that control what data is written. These methods are regeneration, FIFO regeneration and non-regeneration modes. © National Instruments Corporation NI 6236 User Manual...

  • Page 53: Analog Output Triggering

    Analog output supports two different triggering actions: • Start trigger • Pause trigger A digital trigger can initiate these actions. NI 6236 devices support digital triggering, but do not support analog triggering. Refer to the AO Start Trigger Signal AO Pause Trigger Signal sections for more information about these triggering actions.

  • Page 54: Analog Output Timing Signals

    V OUT AO 3 Channel 3 AO GND Figure 5-2. Analog Output Connections Analog Output Timing Signals Figure 5-3 summarizes all of the timing options provided by the analog output timing engine. © National Instruments Corporation NI 6236 User Manual...

  • Page 55: Ao Start Trigger Signal

    Programmable Clock 20 MHz Timebase Divider 100 kHz Timebase PXI_CLK10 Figure 5-3. Analog Output Timing Options NI 6236 devices feature the following AO (waveform generation) timing signals. • AO Start Trigger Signal • AO Pause Trigger Signal • AO Sample Clock Signal •...

  • Page 56: Routing Ao Start Trigger Signal To An Output Terminal

    Analog Output The source also can be one of several internal signals on your DAQ device. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information. You also can specify whether the waveform generation begins on the rising edge or falling edge of ao/StartTrigger.

  • Page 57: Using A Digital Source

    PXI_STAR The source also can be one of several other internal signals on your DAQ device. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information. You also can specify whether the samples are paused when ao/PauseTrigger is at a logic high or low level.

  • Page 58: Using An Internal Source

    When using an internally generated ao/SampleClock, you also can specify a configurable delay from ao/StartTrigger to the first ao/SampleClock pulse. By default, this delay is two ticks of ao/SampleClockTimebase. © National Instruments Corporation NI 6236 User Manual...

  • Page 59: Ao Sample Clock Timebase Signal

    If you want to use an external sample clock signal, but do not need to divide the signal, then you should use ao/SampleClock rather than ao/SampleClockTimebase. NI 6236 User Manual 5-10 ni.com...

  • Page 60: Getting Started With Ao Applications In Software

    DMA data transfer mechanisms. Some of the applications also use start triggers and pause triggers. Note For more information about programming analog output applications and triggers in software, refer to the NI-DAQmx Help or the LabVIEW 8.x Help. © National Instruments Corporation 5-11...

  • Page 61: Digital Input And Output

    Export a timing output signal to a line as a PFI pin The voltage input and output levels and the current drive level of the DI and DO lines are listed in the NI 6236 Specifications. Refer to Chapter 8, PFI, for more information about PFI inputs and outputs.

  • Page 62: Programmable Power-Up States

    If the port powers up enabled, you also can configure each line individually to power up as 1 or 0. Refer to the NI-DAQmx Help or the LabVIEW 8.x Help for more information about setting power-up states in NI-DAQmx or MAX.

  • Page 63: Getting Started With Dio Applications In Software

    Figure 6-1. Digital I/O Connections Caution Exceeding the maximum input voltage or maximum working voltage ratings, which are listed in the NI 6236 Specifications, can damage the DAQ device and the computer. NI is not liable for any damage resulting from such signal connections.
  • Page 64 Counters NI 6236 devices have two general-purpose 32-bit counter/timers and one frequency generator, as shown in Figure 7-1. The general-purpose counter/timers can be used for many measurement and pulse generation applications. Input Selection Muxes Counter 0 Counter 0 Source (Counter 0 Timebase)

  • Page 65: Counters

    You can route the pause trigger to the Gate input of the counter. You can configure the counter to pause counting when the pause trigger is high or when it is low. Figure 7-3 shows an example of on-demand edge counting with a pause trigger. NI 6236 User Manual ni.com...

  • Page 66: Buffered (Sample Clock) Edge Counting

    Gate. Counter Armed Sample Clock (Sample on Rising Edge) SOURCE Counter Value Buffer Figure 7-4. Buffered (Sample Clock) Edge Counting © National Instruments Corporation NI 6236 User Manual...

  • Page 67: Non-Cumulative Buffered Edge Counting

    Always count up • Always count down • Count up when the Counter n B input is high; count down when it is For information about connecting counter signals, refer to the Default Counter Terminals section. NI 6236 User Manual ni.com...

  • Page 68: Pulse-Width Measurement

    SOURCE Counter Value HW Save Register Figure 7-6. Single Pulse-Width Measurement Buffered Pulse-Width Measurement Buffered pulse-width measurement is similar to single pulse-width measurement, but buffered pulse-width measurement takes measurements over multiple pulses. © National Instruments Corporation NI 6236 User Manual...

  • Page 69: Period Measurement

    (or falling) edges occurring on the Source input between the two active edges of the Gate signal. You can calculate the period of the Gate input by multiplying the period of the Source signal by the number of edges returned by the counter. NI 6236 User Manual ni.com...

  • Page 70: Single Period Measurement

    Gate input. So the first value stored in the hardware save register does not reflect a full period of the Gate input. In most applications, this first point should be discarded. Figure 7-9 shows an example of a buffered period measurement. © National Instruments Corporation NI 6236 User Manual...

  • Page 71: Semi-Period Measurement

    You can calculate the semi-period of the Gate input by multiplying the period of the Source signal by the number of edges returned by the counter. Single Semi-Period Measurement Single semi-period measurement is equivalent to single pulse-width measurement. NI 6236 User Manual ni.com...

  • Page 72: Buffered Semi-Period Measurement

    You can choose one of the following methods depending on your application. Method 1—Measure Low Frequency with One Counter In this method, you measure one period of your signal using a known timebase. This method is good for low frequency signals. © National Instruments Corporation NI 6236 User Manual...

  • Page 73: Method 1B-Measure Low Frequency With One Counter (Averaged)

    Recall that the first period measurement in the buffer should be discarded. Average the remaining K period measurements to determine the average period of F1. The frequency of F1 is the inverse of the average period. Figure 7-12 illustrates this method. NI 6236 User Manual 7-10 ni.com...

  • Page 74: Method 2-Measure High Frequency With Two Counters

    T to be N periods of F1. Then the frequency of F1 is N/T. Figure 7-13 illustrates this method. Another option would be to measure the width of a known period instead of a known pulse. © National Instruments Corporation 7-11 NI 6236 User Manual...

  • Page 75: Method 3-Measure Large Range Of Frequencies Using Two Counters

    You can route the signal to measure to the Source input of Counter 0, as shown in Figure 7-14. Assume this signal to measure has frequency F1. Configure Counter 0 to generate a single pulse that is the width of N periods of the source input signal. NI 6236 User Manual 7-12 ni.com...

  • Page 76: Choosing A Method For Measuring Frequency

    However, the accuracy of the measurement decreases as the frequency increases. Consider a frequency measurement on a 50 kHz signal using an 80 MHz Timebase. This frequency corresponds to 1600 cycles of the © National Instruments Corporation 7-13 NI 6236 User Manual...
  • Page 77 (if you cannot provide an external signal of known width). An advantage of Method 2 is that the measurement completes in a known amount of time. • Method 3 measures high and low frequency signals accurately. However, it requires two counters. NI 6236 User Manual 7-14 ni.com...

  • Page 78: Position Measurement

    X2, or X4. Figure 7-15 shows a quadrature cycle and the resulting increments and decrements for X1 encoding. When channel A leads channel B, the © National Instruments Corporation 7-15 NI 6236 User Manual...
  • Page 79 Some quadrature encoders have a third channel, channel Z, which is also referred to as the index channel. A high level on channel Z causes the counter to be reloaded with a specified value in a specified phase of the NI 6236 User Manual 7-16 ni.com...

  • Page 80: Measurements Using Two Pulse Encoders

    The counter supports two pulse encoders that have two channels—channels A and B. The counter increments on each rising edge of channel A. The counter decrements on each rising edge of channel B, as shown in Figure 7-19. © National Instruments Corporation 7-17 NI 6236 User Manual...

  • Page 81: Two-Signal Edge-Separation Measurement

    The counter then stores the count in a hardware save register and ignores other edges on its inputs. Software then can read the stored count. Figure 7-20 shows an example of a single two-signal edge-separation measurement. NI 6236 User Manual 7-18 ni.com...

  • Page 82: Buffered Two-Signal Edge-Separation Measurement

    Figure 7-21 shows an example of a buffered two-signal edge-separation measurement. GATE SOURCE Counter Value Buffer Figure 7-21. Buffered Two-Signal Edge-Separation Measurement For information about connecting counter signals, refer to the Default Counter Terminals section. © National Instruments Corporation 7-19 NI 6236 User Manual...

  • Page 83: Counter Output Applications

    After the Start Trigger signal pulses once, the counter ignores the Gate input. Figure 7-23 shows a generation of a pulse with a pulse delay of four and a pulse width of three (using the rising edge of Source). NI 6236 User Manual 7-20 ni.com...

  • Page 84: Retriggerable Single Pulse Generation

    (using the rising edge of Source). GATE (Start Trigger) SOURCE Figure 7-24. Retriggerable Single Pulse Generation For information about connecting counter signals, refer to the Default Counter Terminals section. © National Instruments Corporation 7-21 NI 6236 User Manual...

  • Page 85: Pulse Train Generation

    Counter n Internal Output signal is equal to the frequency of the Source input divided by M + N. For information about connecting counter signals, refer to the Default Counter Terminals section. NI 6236 User Manual 7-22 ni.com...

  • Page 86: Frequency Generation

    Figure 7-27 shows the output waveform of the frequency generator when the divider is set to 5. Frequency Output Timebase Freq Out (Divisor = 5) Figure 7-27. Frequency Generator Output Waveform © National Instruments Corporation 7-23 NI 6236 User Manual...

  • Page 87: Frequency Division

    Gate edge is in progress. The waveform thus produced at the counter’s output can be used to provide timing for undersampling applications where a digitizing system can sample repetitive waveforms that are higher in frequency than the Nyquist NI 6236 User Manual 7-24 ni.com...

  • Page 88: Counter Timing Signals

    Counter 0) and Counter 1 Source (the source input to Counter 1). Counter n Source Signal The selected edge of the Counter n Source signal increments and decrements the counter value depending on the application the counter is © National Instruments Corporation 7-25 NI 6236 User Manual...

  • Page 89: Routing A Signal To Counter N Source

    Some of these options may not be available in some driver software. Routing Counter n Source to an Output Terminal You can route Counter n Source out to any output PFI <6..9> or RTSI <0..7> terminal. All PFIs are set to high-impedance at startup. NI 6236 User Manual 7-26 ni.com...

  • Page 90: Counter N Gate Signal

    Each counter has independent input selectors for the Counter n Aux signal. Any of the following signals can be routed to the Counter n Aux input. • RTSI <0..7> • Input PFI <0..5> • ai/ReferenceTrigger © National Instruments Corporation 7-27 NI 6236 User Manual...

  • Page 91: Counter N A, Counter N B, And Counter N Z Signals

    To begin any counter input or output function, you must first enable, or arm, the counter. In some applications, such as buffered semi-period measurement, the counter begins counting when it is armed. In other applications, such as single pulse-width measurement, the counter begins NI 6236 User Manual 7-28 ni.com...

  • Page 92: Routing Signals To Counter N Hw Arm Input

    The Frequency Output (FREQ OUT) signal is the output of the frequency output generator. Routing Frequency Output to a Terminal You can route Frequency Output to any output PFI <6..9> terminal. All PFIs are set to high-impedance at startup. © National Instruments Corporation 7-29 NI 6236 User Manual...

  • Page 93: Default Counter Terminals

    You can use these defaults or select other sources and destinations for the counter/timer signals in NI-DAQmx. Refer to Connecting Counter Signals in the NI-DAQmx Help or the LabVIEW 8.x Help for more information about how to connect your signals for common counter measurements and generations.

  • Page 94: Counter Triggering

    When using a pause trigger, the pause trigger source is routed to the Counter n Gate signal input of the counter. © National Instruments Corporation 7-31 NI 6236 User Manual...

  • Page 95: Other Counter Features

    M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency. Note NI-DAQmx only supports filters on counter inputs. The following is an example of low to high transitions of the input signal.

  • Page 96: Prescaling

    Source and puts out a frequency that is one-eighth (or one-half) of what it is accepting. External Signal Prescaler Rollover (Used as Source by Counter) Counter Value Figure 7-30. Prescaling © National Instruments Corporation 7-33 NI 6236 User Manual...

  • Page 97: Duplicate Count Prevention

    On the first rising edge of the Gate, the current count of 7 is stored. On the next rising edge of the Gate, the counter stores a 2 since two Source pulses occurred after the previous rising edge of Gate. NI 6236 User Manual 7-34 ni.com...

  • Page 98: Example Application That Works Incorrectly (Duplicate Counting)

    Gate even if the Source does not pulse. This enables the correct current count to be stored in the buffer even if no Source edges occur between Gate signals, as shown in Figure 7-33. © National Instruments Corporation 7-35 NI 6236 User Manual...

  • Page 99: When To Use Duplicate Count Prevention

    The frequency of the external source is 20 MHz or less • You can have the counter value and output to change synchronously with the 80 MHz Timebase In all other cases, you should not use duplicate count prevention. NI 6236 User Manual 7-36 ni.com...

  • Page 100: Enabling Duplicate Count Prevention In Ni-Daqmx

    Chapter 7 Counters Enabling Duplicate Count Prevention in NI-DAQmx You can enable duplicate count prevention in NI-DAQmx by setting the Enable Duplicate Count Prevention attribute/property. For specific information about finding the Enable Duplicate Count Prevention attribute/property, refer to the help file for the API you are using.

  • Page 101: 80 Mhz Source Mode

    Source signal, and counts on the following rising edge of the source, as shown in Figure 7-36. Source Synchronize Delayed Source Count Figure 7-36. External Source Mode NI 6236 User Manual 7-38 ni.com...

  • Page 102: Pfi

    NI 6236 devices have 10 Programmable Function Interface (PFI) signals—six input signals and four output signals. Each PFI <0..5>/P0.<0..5> can be configured as a timing input signal for AI or counter/timer functions or a static digital input. Each PFI input also has a programmable debouncing filter.

  • Page 103: Using Pfi Terminals As Timing Input Signals

    P0.x or P1.x. The voltage input and output levels and the current drive levels of the PFI signals are listed in the NI 6236 Specifications. Using PFI Terminals as Timing Input Signals Use PFI <0..5> terminals to route external timing signals to many different M Series functions.

  • Page 104: Exporting Timing Output Signals Using Pfi Terminals

    All PFI input connections are referenced to D GND. Figure 8-3 shows this reference, and how to connect an external PFI 0 source and an external PFI 2 source to two PFI terminals. © National Instruments Corporation NI 6236 User Manual...

  • Page 105: Pfi Filters

    M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency. Note NI-DAQmx only supports filters on counter inputs. The following is an example of low to high transitions of the input signal.
  • Page 106 Refer to the KnowledgeBase document, Digital Filtering with M Series, for more information about digital filters and counters. To access this KnowledgeBase, go to and enter the info code ni.com/info rddfms © National Instruments Corporation NI 6236 User Manual...

  • Page 107: I/O Protection

    If the port powers up enabled, you also can configure each line individually to power up as 1 or 0. Refer to the NI-DAQmx Help or the LabVIEW 8.x Help for more information about setting power-up states in NI-DAQmx or MAX.

  • Page 108: Isolation And Digital Isolators

    All analog and digital signals are made relative to the isolated ground signal. The isolated ground is an input to the NI 6236 device. The user must connect this ground to the ground of the system being measured or controlled.

  • Page 109: Digital Isolation

    Digital Isolation The NI 6236 uses digital isolators. Unlike analog isolators, digital isolators do not introduce any analog error in the measurements taken by the device. The A/D converter, used for analog input, is on the isolated side of the device.

  • Page 110: Creating An Ac Return Path

    The voltage rating of the capacitor must be larger than the voltage drop between the isolated ground and earth ground. © National Instruments Corporation NI 6236 User Manual...

  • Page 111: Digital Routing And Clock Generation

    ÷ 8 80 MHz Output Selectors) Oscillator External 80 MHz Timebase Reference RTSI <0..7> Clock PXI_CLK10 20 MHz Timebase ÷ PXI_STAR 100 kHz Timebase ÷ Figure 10-1. M Series Clock Routing Circuitry © National Instruments Corporation 10-1 NI 6236 User Manual...

  • Page 112: 80 Mhz Timebase

    The following signals can be routed to drive the external reference clock. • RTSI <0..7> • PXI_CLK10 • PXI_STAR The external reference clock is an input to a Phase-Lock Loop (PLL). The PLL generates the internal timebases. NI 6236 User Manual 10-2 ni.com...

  • Page 113: 10 Mhz Reference Clock

    Real-Time System Integration (RTSI) is set of bused signals among devices that allow you to do the following. • Use a common clock (or timebase) to drive the timing engine on multiple devices • Share trigger signals between devices © National Instruments Corporation 10-3 NI 6236 User Manual...

  • Page 114: Rtsi Connector Pinout

    Figure 10-2 shows the RTSI connector pinout and Table 10-1 describes the RTSI signals. The RTSI signals are referenced to earth/chassis ground; they are not isolated. Terminal 34 Terminal 33 Terminal 2 Terminal 1 Figure 10-2. NI 6236 RTSI Pinout NI 6236 User Manual 10-4 ni.com...

  • Page 115: Using Rtsi As Outputs

    10 MHz Reference Clock • Counter n Source, Gate, Z, Internal Output • FREQ OUT • Input PFI <0..5> Note Signals with a * are inverted before being driven on the RTSI terminals. © National Instruments Corporation 10-5 NI 6236 User Manual...

  • Page 116: Using Rtsi Terminals As Timing Input Signals

    M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency. Note NI-DAQmx only supports filters on counter inputs. The following is an example of low to high transitions of the input signal.
  • Page 117 Refer to the KnowledgeBase document, Digital Filtering with M Series, for more information about digital filters and counters. To access this KnowledgeBase, go to and enter the info code ni.com/info rddfms © National Instruments Corporation 10-7 NI 6236 User Manual...

  • Page 118: Pxi Clock And Trigger Signals

    An M Series device receives the Star Trigger signal (PXI_STAR) from a Star Trigger controller. PXI_STAR can be used as an external source for many AI, AO, and counter signals. NI 6236 User Manual 10-8 ni.com...

  • Page 119: Pxi_Star Filters

    M Series devices use an onboard oscillator to generate the filter clock with a 40 MHz frequency. Note NI-DAQmx only supports filters on counter inputs. The following is an example of low to high transitions of the input signal.
  • Page 120 PFI, the M Series device does not use the filtered version of the input signal. Refer to the KnowledgeBase document, Digital Filtering with M Series, for more information about digital filters and counters. To access this KnowledgeBase, go to and enter the info code ni.com/info rddfms NI 6236 User Manual 10-10 ni.com...

  • Page 121: Bus Interface

    Bus Interface The bus interface circuitry of NI 6236 devices efficiently moves data between host memory and the measurement and acquisition circuits. NI 6236 devices are available for the following platforms. • • NI 6236 devices are jumperless for complete plug-and-play operation. The operating system automatically assigns the base address, interrupt levels, and other resources.

  • Page 122: Pxi Considerations

    Generation, for more information about PXI clock and trigger signals. PXI and PXI Express NI PXI-6236 modules can be installed in any PXI chassis and most slots of PXI Express chassis. PXI specifications are developed by the PXI System Alliance ).

  • Page 123: Using Pxi With Compactpci

    Caution Damage can result if these lines are driven by the sub-bus. NI is not liable for any damage resulting from improper signal connections.

  • Page 124: Interrupt Request (Irq)

    (that is, AI, AO, and so on) has a dedicated DMA channel. So in most applications, all data transfers use DMA. However, NI-DAQmx allows you to disable DMA and use interrupts. To change your data transfer mechanism between DMA and interrupts in NI-DAQmx, use the Data Transfer Mechanism property node.

  • Page 125: Triggering

    When you configure a trigger, you must decide how you want to produce the trigger and the action you want the trigger to cause. NI 6236 devices support internal software triggering, as well as external digital triggering. For information about the different actions triggers can perform for each sub-system of the device, refer to the following sections: •...
  • Page 126 You also can program your DAQ device to perform an action in response to a trigger from a digital source. The action can affect the following. • Analog input acquisition • Analog output generation • Counter behavior NI 6236 User Manual 12-2 ni.com...

  • Page 127: Ni 6236 Device Information

    NI 6236 Device Information This appendix contains device pinouts, specifications, cable and accessory choices, and other information for the NI 6236 M Series devices. To obtain documentation for devices not listed here, refer to ni.com/manuals NI 6236 Pinout Figure A-1 shows the pinout of the NI 6236.
  • Page 128 PFI 7/P1.1 (Output) D GND PFI 8/P1.2 (Output) PFI 9/P1.3 (Output) NC = No Connect Figure A-1. NI 6236 Pinout Table A-1. NI 6236 Device Default NI-DAQmx Counter/Timer Pins Counter/Timer Signal Default Pin Number (Name) Port CTR 0 SRC 13 (PFI 0) P0.0...

  • Page 129: Ni 6236 Specifications

    Screw Terminal National Instruments offers several styles of screw terminal connector blocks. Use an SH37F-37M cable to connect an NI 6236 device to a connector block, such as the following: • CB-37F-HVD—37-pin DIN rail screw terminal block, UL Recognized derated to 30 Vrms, 42.4 V...
  • Page 130 Appendix A NI 6236 Device Information RTSI Use RTSI bus cables to connect timing and synchronization signals among PCI devices, such as M Series, E Series, CAN, and other measurement, vision, and motion devices. Since PXI devices use PXI backplane signals for timing and synchronization, no cables are required.

  • Page 131: Appendix B Troubleshooting

    National Instruments KnowledgeBase at . It contains thousands of documents that ni.com/kb answer frequently asked questions about NI products. Analog Input I am seeing crosstalk or ghost current when sampling multiple channels. What does this mean?
  • Page 132 These glitches are normal; when a DAC switches from one voltage to another, it produces glitches due to released charges. The largest glitches occur when the most significant bit of the DAC code NI 6236 User Manual ni.com...

  • Page 133: Counters

    Chapter 7, Counters, for more information. How do I connect counter signals to my M Series device? Default Counter Terminals section of Chapter 7, Counters, has information about counter signal connections. © National Instruments Corporation NI 6236 User Manual...

  • Page 134: Technical Support And Professional Services

    – Free Technical Support—All registered users receive free Basic Service, which includes access to hundreds of Application Engineers worldwide in the NI Developer Exchange at . National Instruments Application Engineers ni.com/exchange make sure every question receives an answer.
  • Page 135 NI corporate headquarters. Phone numbers for our worldwide offices are listed at the front of this manual. You also can visit the Worldwide Offices section of to access the branch ni.com/niglobal...

  • Page 136: Glossary

    A measure of the capability of an instrument or sensor to faithfully indicate the value of the measured signal. This term is not related to resolution; however, the accuracy level can never be better than the resolution of the instrument. Application development environment. © National Instruments Corporation NI 6236 User Manual...
  • Page 137 The process of getting an instrument ready to perform a function. For example, the trigger circuitry of a digitizer is armed, meaning that it is ready to start acquiring data when an appropriate trigger condition is met. NI 6236 User Manual ni.com...
  • Page 138 The process of determining the accuracy of an instrument. In a formal sense, calibration establishes the relationship of an instrument’s measurement to the value provided by a standard. When that relationship is known, the instrument may then be adjusted (calibrated) for best accuracy. © National Instruments Corporation NI 6236 User Manual...
  • Page 139 A symbol that connects points on a flowchart. convert rate Reciprocal of the interchannel delay. count The number of events, such as zero crossings, pulses, or cycles. NI 6236 User Manual ni.com...
  • Page 140 ) port. SCXI modules are considered DAQ devices. DAQ-STC2 Data acquisition system timing controller chip. data acquisition The general concept of acquiring data, as in begin data acquisition or data acquisition and control. See also DAQ. © National Instruments Corporation NI 6236 User Manual...
  • Page 141 The capability of an instrument to generate and acquire digital signals. Static digital I/O refers to signals where the values are set and held, or rarely change. Dynamic digital I/O refers to digital systems where the signals are continuously changing, often at multi-MHz clock rates. NI 6236 User Manual ni.com...
  • Page 142 A voltage pulse from an external source that causes a DAQ operation to begin. EXTREF External reference signal. © National Instruments Corporation NI 6236 User Manual...
  • Page 143 Also called non-referenced signal sources. Some common examples of floating signal sources are batteries, transformers, and thermocouples. FREQ OUT Frequency Output signal. frequency The number of alternating signals that occur per unit time. Feet. NI 6236 User Manual ni.com...
  • Page 144 Input/Output—The transfer of data to/from a computer system involving communications channels, operator interface devices, and/or data acquisition and control interfaces. impedance 1. The electrical characteristic of a circuit expressed in ohms and/or capacitance/inductance. 2. Resistance. © National Instruments Corporation NI 6236 User Manual...
  • Page 145 An electrical break between any two signals or planes up to a given voltage. isolation barrier An electrical break between two electrical planes providing a given or set amount of electrical isolation. Current does not flow or transfer between the two sides of the isolation barrier. NI 6236 User Manual G-10 ni.com...
  • Page 146 An MIO product can be considered a miniature mixed signal tester, due to its broad range of signal types and flexibility. Also known as multifunction DAQ. © National Instruments Corporation G-11 NI 6236 User Manual...
  • Page 147 SCXI components. Some devices use Traditional NI-DAQ (Legacy); others use NI-DAQmx. NI-DAQmx The latest NI-DAQ driver with new VIs, functions, and development tools for controlling measurement devices. The advantages of NI-DAQmx over earlier versions of NI-DAQ include the DAQ Assistant for configuring channels and measurement tasks for your device for use in LabVIEW, LabWindows/CVI, and Measurement Studio;...
  • Page 148 2. A digital port, consisting of four or eight lines of digital input and/or output. posttriggering The technique used on a DAQ device to acquire a programmed number of samples after trigger conditions are met. © National Instruments Corporation G-13 NI 6236 User Manual...
  • Page 149 90° from each other. This makes it possible to detect the direction of the motion. range The maximum and minimum parameters between which a sensor, instrument, or device operates with a specified set of characteristics. This may be a voltage range or a frequency range. NI 6236 User Manual G-14 ni.com...
  • Page 150 Controls how often a scan is initialized; is regulated by the AI Sample Clock signal. scan rate Reciprocal of the scan interval. Signal Conditioning Carriers—A compact, modular form factor for signal conditioning modules. © National Instruments Corporation G-15 NI 6236 User Manual...
  • Page 151 ‘housekeeping’ of the machine, which is independent of any specific application. Operating system functions include the saving of data (file system), handling of multiple programs at the same time (multi-tasking), network interconnection, printing, and keyboard/user interface interaction. NI 6236 User Manual G-16 ni.com...
  • Page 152 In NI-DAQmx, a collection of one or more channels, timing, and triggering and other properties that apply to the task itself. Conceptually, a task represents a measurement or generation you want to perform.
  • Page 153 USB 2.0 retains compatibility with the original USB specification. Volts. Common-mode voltage. Ground loop voltage. Volts, input high. Volts, input low. Volts in. Measured voltage. Volts, output high. Volts, output low. NI 6236 User Manual G-18 ni.com...
  • Page 154 Signal source voltage. virtual channel See channel. waveform 1. The plot of the instantaneous amplitude of a signal as a function of time. 2. Multiple voltage readings taken at a specific sampling rate. © National Instruments Corporation G-19 NI 6236 User Manual...
  • Page 155 5-4 AI timing signals, 4-12 data generation methods, 5-2 ai/ConvertClock, 4-17 getting started with applications in ai/ConvertClockTimebase, 4-20 software, 5-11 ai/HoldCompleteEvent, 4-20 glitches on the output signal, 5-2 ai/PauseTrigger, 4-23 signals, 5-5 © National Instruments Corporation NI 6236 User Manual...
  • Page 156 2-4, A-3 triggering, 5-4 choosing for your device, 1-2 troubleshooting, B-2 custom, 2-4 ANSI C documentation, xvi calibration certificate (NI resources), C-2 AO FIFO, 5-2 calibration circuitry, 2-3 AO Pause Trigger signal, 5-7 cascading counters, 7-32 AO Sample Clock signal, 5-8...
  • Page 157 7-30 DMA, 11-3 counters IRQ, 11-4 cascading, 7-32 programmed I/O, 11-4 duplicate count prevention, 7-34 Declaration of Conformity (NI resources), C-1 edge counting, 7-2 default counter terminals, 7-30 filters, 7-32 device generation, 7-20 cabling, 2-4 input applications, 7-2...
  • Page 158 6-2 X2, 7-16 source, triggering, 12-1 X4, 7-16 digital I/O equivalent time sampling, 7-24 circuitry, 6-1 examples (NI resources), C-1 connecting signals, 6-2 exporting timing output signals using PFI terminals, 8-3 getting started with applications in software, 6-3 external...
  • Page 159 7-8 NI-DAQ, 1-1 single two-signal edge-separation, 7-18 other software, 1-1 two-signal edge-separation, 7-18 instrument drivers (NI resources), C-1 using quadrature encoders, 7-15 interface, bus, 11-1 using two pulse encoders, 7-17 interrupt request, as a transfer method, 11-4 © National Instruments Corporation...
  • Page 160 A-1 signals, 8-2 pinout, A-1 pin assignments. See pinouts specifications, A-3 pinouts, 1-1 NI support and services, C-1 device, 1-1 NI-DAQ documentation, xiv NI 6236, A-1 device documentation browser, xvii RTSI connector, 3-2, 10-4 NI-DAQmx Base documentation, xv...
  • Page 161 RTSI, 10-3 Counter n A, 7-28 connector pinout, 3-2, 10-4 Counter n Aux, 7-27 filters, 10-6 Counter n B, 7-28 using as outputs, 10-5 Counter n Gate, 7-27 Counter n HW Arm, 7-28 © National Instruments Corporation NI 6236 User Manual...
  • Page 162 PFI period measurement, 7-7 terminals, 8-3 pulse generation, 7-20 training, xvii retriggerable, 7-21 training and certification (NI resources), C-1 with start trigger, 7-20 transducers, 2-3 pulse-width measurement, 7-5 triggering, 12-1 semi-period measurement, 7-8 analog input, 4-11...
  • Page 163 8-2 to export timing output signals, 8-3 using RTSI X1 encoding, 7-15 as outputs, 10-5 X2 encoding, 7-16 terminals as timing input signals, 10-6 X4 encoding, 7-16 using short high-quality cabling, 4-8 © National Instruments Corporation NI 6236 User Manual...

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