Data Acquisition and Signal Conditioning Counter/Timer Overview Counter/Timer Overview You can use the versatile National Instruments counter/timer devices to create a wide variety of measurement solutions, including measuring a number of time-related quantities, counting events or totalizing, and monitoring position with quadrature encoders. You can also use counter/timers to generate pulses and pulse trains. Counter/timers often fulfill critical timing functions as components of complex measurement systems. The NI 660x counter/timers use the NI-TIO, a National Instruments ASIC chip specifically designed to meet the counting and timing requirements of measurement applications that are beyond the capabilities of off-the-shelf components. The wider functionality and simple programming interface make the NI 660x your best choice for counting and timing applications. Example applications include frequency measurement, position measurement, generation of retriggerable pulses, frequency shiftkeying, two-signal edge separation measurements, continuous buffered event counting, and continuous buffered pulse train measurements. The NI 660x counter/timer devices are readily integrated into measurement systems that require synchronization across multiple hardware devices because they are equipped with the National Instruments PXI trigger bus or the RTSI bus. See the counter/timer tutorial on page 789 for more information. In addition to counter/timer functionality, the NI 660x products include TTL/CMOS-compatible digital I/O ports that are bit configurable for input or output. Counter/Timer Size or Number of Bits The counter size or number of bits indicates how high a counter can count. For example, a 32-bit counter can count up to 232-1 or 4,294,967,295 before it rolls over. A high number of bits is beneficial in cases such as pulse width measurements where a wide dynamic range is required. For example, if you measure pulse widths with a 12.5 ns resolution (80 MHz timebase) using a counter/timer with 32 bits, you can measure pulse widths up to 53 s [(232-1) x 12.5 ns)] with 12.5 ns resolution. Maximum Source Frequency Counter/Timer Considerations Number of Counter/Timers The counter/timer is a basic unit of hardware functionality on a measurement device. The more counter/timers there are on a device, the more counting/timing operations that device can simultaneously perform. The number of DMA channels determines how many buffered, high-speed operations can be simultaneously performed. See page 393 for more information. Family NI 6601 NI 6602 NI 6608 Bus PCI PCI PXI PXI Counter/ Timers 4 8 8 Size 32 bits 32 bits Max Source Frequency 20 MHz1 80 MHz1 Compatibility 5 V TTL/CMOS 5 V TTL/CMOS 32 bits 80 MHz1 5 V TTL/CMOS Maximum source frequency represents the speed of the fastest signal the counter can count. If you use a higher source frequency, you can achieve higher resolution. For example, an 80 MHz counter can count pulses that are 12.5 ns (1⁄80 x 10 ) apart. You can use prescalers to increase the maximum source frequency for event counting and frequency measurement. 6 Digital I/O Up to 32 Up to 32 Pulse Generation ✓ ✓ Buffered Operations ✓ ✓ Up to 32 ✓ ✓ 1Max Debouncing/ Glitch Oscillator Removal Stability ✓ 50 ppm ✓ 50 ppm ✓ 75 ppb GPS Synchr. – – ✓ Buffered Operations2 DMA Interrupt 1 3 3 5 3 Source Frequency with prescalers is 60 MHz for the NI 6601 and 125 MHz for the NI 6602 and NI 6608. These frequencies are dependent on drive strength of input signal and cable length. Consider these speeds to be the maximum. 2DMA transfers have higher throughput than interrupt transfers. See page 393 for detailed specifications. 386 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 5 Page 388 388 388 Counter/Timer Overview Signal compatibility indicates the signal levels a counter/timer can measure or output, such as TTL/CMOS. Buffered Operations and DMA Timebase Stability Timebase stability can be important when you need to make highquality measurements. Crystal oscillators typically form the basis of electrical circuits used to drive timing of a measurement application. In an ideal case, the oscillation frequency would be constant, but in reality, many factors influence the the behavior of an oscillator. A commonly used measure of quality for an oscillator is stability. Start of Measurement Debouncing and Glitch Removal Noisy signals containing glitches and/or bouncing effects pose special challenges for some counter/timer measurements. Noise may be introduced in the source of the signal, such as with electromechanical relays, or in the connection if there are strong sources of interference in the vicinity of the system. NI 660x devices contain programmable digital filters that eliminate measurement errors caused by spurious spikes and bouncing. Figure 2 shows an example of digital filtering. Calibration Calibration is a key component of any measurement solution. In the case of counter/timers, timebase calibration ensures that the frequency and time measurements are accurate. Calibration certificates enclosed with the National Instruments counter/timers and periodic calibration satisfy your ISO-9000 requirements, certifying that your instrument has been properly calibrated. See page 21 for more information. Data Acquisition and Signal Conditioning The National Instruments counter/timers can capture numerous data points without dead times. These types of measurements, called buffered operations, are valuable in applications that range from statistical analysis on production lines to experiments in molecular chemistry. For instance, when you configure a counter for buffered period measurement, data is moved from the counter into a buffer. Each edge that initiates a measurement also causes a transfer of the count into the buffer, as shown in Figure 1. With buffered operations, data is transferred to the computer memory using DMA or interrupts. DMA offers a considerable performance advantage; if your application requires this performance simultaneously on multiple counter/timers, you must know how many DMA channels are available on a particular counter/timer device. For example, if a device contains three DMA channels and eight counter/timers, you can simultaneously perform three high-speed and five lowerspeed, interrupt-based, buffered operations. On NI 660x devices, National Instruments implements DMA with the NI MITE chip, which is optimized for measurement applications. Units used for stability are typically parts per million (ppm) and parts per billion (ppb). For example, the frequency of a 10 MHz oscillator with 10 ppm stability can be 10 MHz ± 100 Hz; with 100 ppb stability it can be 10 MHz ± 1 Hz. The best technique for improving oscillator stability is to precisely control its temperature as is done in an oven-controlled crystal oscillator (OCXO). The PXI-6608 features such an oscillator. Counter/Timer Overview Signal Compatibility Input Filtered Output T1 T2 T3 Figure 2. Debouncing and Glitch Removal T4 Input Signal T1 T1 T1 T1 T2 T2 T2 T3 T3 Measurement Data Buffer T4 Figure 1. Buffered Period Measurement with Counter/Timers National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 387 32-Bit Counter/Timers 32-Bit Counter/Timers NI 660x • Up to eight 32-bit counter/timers • 80 MHz maximum source frequency (125 MHz with prescalers) • Debouncing and glitch removal • High-stability timebase (PXI-6608 only) • GPS-based synchronization (PXI-6608 only) • NI DAQ driver simplifies configuration and measurements Models Operating Systems • Windows 2000/NT/XP • Real-time performance with LabVIEW (p. 134) • Others such as Linux and Mac OS X (page 187) Recommended Software • LabVIEW • LabWindows/CVI • Measurement Studio Other Compatible Software • NI PCI-6601 • NI PCI-6602 • NI PXI-6602 • NI PXI-6608 • Visual Basic • Visual C/C++, C# Driver Software (included) • NI-DAQ 7 Calibration Certificate Included See page 21. Data Acquisition and Signal Conditioning Overview and Applications NI 660x devices are timing and digital I/O (DIO) modules for PCI and PXI. They offer up to eight 32-bit counter/timers and up to 32 lines of 5 V TTL/CMOS-compatible digital I/O. You can perform a wide variety of buffered measurements or other counter/timer tasks with NI 660x devices, including position or quadrature encoder measurement, event counting, period measurement, pulse-width measurement, frequency measurement, pulse generation, and pulsetrain generation. Features Counter/Timers The PCI-6601 board features one NI-TIO ASIC for a total of four counter/timers. The counters are software-compatible with those found on E Series multifunction DAQ devices, but NI 660x devices offer additional capabilities. Each counter has a gate, up/down, and source signal, which can be controlled by external or internal signals. Each counter has one output that can be routed externally or to other counters on the device. 20 MHz and 100 kHz timebases are available on each device for use with each counter/timer. In addition, an 80 MHz timebase is available on the NI 6602 and NI 6608 devices. A hardware trigger can be used to start multiple counters simultaneously. See Table 1 for more information. The NI 660x devices are equipped with the NI-TIO ASIC, a National Instruments counter and digital I/O ASIC for advanced timing and counting applications. Each NI 6602 and NI 6608 device features two NI-TIO ASICs to provide a total of eight counter/timers. Family NI 6601 NI 6602 NI 6608 Bus PCI PCI PXI PXI Counter/ Timers 4 8 8 Size 32 bits 32 bits Max Source Frequency 20 MHz1 80 MHz1 Compatibility 5 V TTL/CMOS 5 V TTL/CMOS 32 bits 80 MHz1 5 V TTL/CMOS Digital I/O Up to 32 Up to 32 Pulse Generation ✓ ✓ Buffered Operations ✓ ✓ Up to 32 ✓ ✓ 1Max Debouncing/ Glitch Oscillator Removal Stability ✓ 50 ppm ✓ 50 ppm ✓ 75 ppb GPS Synchr. – – ✓ Buffered Operations2 DMA Interrupt 1 3 3 5 3 5 Source Frequency with prescalers is 60 MHz for the NI 6601 and 125 MHz for the NI 6602 and NI 6608. These frequencies are dependent on drive strength of input signal and cable length. Consider these speeds to be the maximum. 2DMA transfers have higher throughput than interrupt transfers. Table 1. NI 660x Products Specifications Summary (See page 393 for detailed specifications.) 388 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 32-Bit Counter/Timers Synchronizing Networked Measurements with GPS The NI PXI-6608 module includes a high-stability 10 MHz oven-controlled crystal oscillator (OCXO) for high-precision applications. When the PXI-6608 is installed in the star trigger slot of a PXI chassis (Slot 2), you can drive the OCXO signal to the PXI backplane for high-stability timing of your entire measurement system. The PXI-6602 and PXI-6608 feature phase-lock loop (PLL) circuitry so that the devices can synchronize their reference clocks to the backplane. You can correlate measurements performed in a wide area using the Global Positioning System (GPS). With the PXI-6608, you can correlate data from several PXI chassis, determine the time when a hardware event occurs, or generate a pulse at a user-specified time. Debouncing and Glitch Removal Each input on the NI 660x devices can be passed through a digital debouncing filter to eliminate glitches on the input signal. You can use defined filter settings to remove noise/glitches narrower than 2.5 µs, 500 ns, 250 ns, and 50 ns from your input signal, or you can use one of the counters to create custom filter settings. Buffered Measurements The NI 660x devices each have a 68-pin shielded, latching connector, with a SOURCE, GATE, UP/DOWN, and OUT signal for each of the counter/timers. PFI<8..31> can be used as general-purpose DIO lines when not used as counter/timer I/O signals. The DIOn lines are the eight dedicated DIO lines. The PCI-6601 devices have the same I/O interface, except that only counters 0-3 are present. Driver Software With NI-DAQ driver software, you can configure your devices interactively, write custom programs, and perform counter/timer I/O easily. NI-DAQ provides the counter/timer functions natively, so you can programmatically select whether you want to measure position with a quadrature encoder, measure a frequency, output a pulse train, or perform one of the other provided counter/timer functions. NI-DAQ also includes numerous example programs for LabVIEW and other ADEs to quickly get you started with your application. Ordering Information Digital I/O The NI-TIO ASIC also provides up to 32 DIO lines on the NI 660x devices. Eight lines are dedicated to DIO, while the others can be used for DIO when not used by the counter/timers. DIO lines are individually software configurable for input or output. RTSI Bus and PXI Trigger Bus NI 660x devices are equipped with the RTSI bus or PXI trigger bus for multidevice synchronization. Timing signals on an NI 660x device can be routed to or from other devices in your system to perform advanced timing and synchronization. PFI31/SOURCE2 GND 34 33 68 67 PFI28/OUT2 32 31 66 65 30 29 28 64 63 62 27 26 61 60 25 24 23 22 21 20 19 18 59 58 57 56 55 54 53 52 17 16 15 14 13 51 50 49 48 47 PFI10/GATE7 12 11 46 45 GND 10 9 8 44 43 42 41 40 39 38 37 36 GND PFI37/UP_DOWN0 GND PFI38/GATE0 PFI39/SOURCE0 7 6 5 4 3 2 +5V 1 35 Reserved PFI27/SOURCE3 GND PFI24/OUT3 PFI23/SOURCE4 GND PFI20/OUT4 PFI19/SOURCE5 GND PFI16/OUT5 PFI15/SOURCE6 PFI14/GATE6 GND Reserved GND PFI9/UP_DOWN7 PFI8/OUT7 PFI7/DIO7 GND PFI4/DIO4 PFI3/DIO3 GND PFI0/DIO0 PFI32/OUT1 PFI34/GATE1 PFI35/SOURCE1 PFI33/UP_DOWN1 PFI36/OUT0 Reserved GND PFI30/GATE2 PFI29/UP_DOWN2 GND PFI26/GATE3 PFI25/UP_DOWN3 GND NI PCI-6601 ..................................................................777918-01 NI PCI-6602 ..................................................................777531-01 NI PXI-6602 ..................................................................777557-01 NI PXI-6608 ..................................................................777937-01 Data Acquisition and Signal Conditioning NI 660x devices use the National Instruments MITE bus interface controller to implement bus-master DMA transfers. As a result, you can perform high-speed, continuous operations such as buffered position encoder measurement and buffered period measurement. You can perform one high-speed DMA-based transfer on the NI 6601 devices and up to three simultaneous DMA transfers on the NI 6602 and NI 6608 devices. You can use interrupts for additional simultaneous buffered transfers. I/O Connector 32-Bit Counter/Timers High-Stability, Oven-Controlled Oscillator Includes NI-DAQ driver software and calibration certificate. PFI22/GATE4 PFI21/UP_DOWN4 GND PFI18/GATE5 For information on extended warranty and value-added services, see page 20. PFI17UP_DOWN5 Recommended Configurations Reserved GND PFI13/UP_DOWN6 PFI12/OUT6 PFI11/SOURCE7 GND GND PFI6/DIO6 PFI5/DIO5 PFI2/DIO2 PFI1/DIO1 Reserved GND Family NI 6601 NI 6602 NI 6608 DAQ Device PCI-6601 PCI-6602 PXI-6602 PXI-6608 Accessory CB-68LP (777145-01) BNC-2121 (778289-01) TB-2715 (778242-01) TB-2715 (778242-01) Cable SH68-68-D1 (183432-01) SH68-68-D1 (183432-01) None required None required See page 390 for accessory and cable information. BUY ONLINE! Visit ni.com/info and enter pci6601, pci6602, pxi6602, and/or pxi6608. Reserved Reserved GND Figure 1. NI 660x I/O Connector National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 389 Counter/Timer Accessories and Cables Counter/Timer Accessories and Cables Accessory and Cable Selection Process Step 1. Select your counter/timer device from Tables 1 and 2. Step 2. Using Tables 1 and 2 as a guide, determine which accessories are appropriate for that device. Select an accessory using Table 3 as reference. Step 3. Using Tables 1 and 2, determine the appropriate cable solution for your selected counter/timer device and accessory. Accessories Figure 1. BNC-2121 Connector Block Connector block with BNC and spring terminal connections for easy connection of I/O signals to counter/timer devices. The BNC-2121 offers spring terminals, as well as eight dedicated and six user-defined BNC connectors, which provide access to all I/O signals. This connector block is also a full-featured test accessory that provides pulse-train, trigger, and quadrature encoder signals. For the connections, refer to the BNC-2121 user guide at ni.com/manuals BNC-2121 ......................................................................................................778289-01 Dimensions – 26.7 by 11.2 by 5.5 cm (8.0 by 4.4 by 2.2 in.) Figure 2. CA-1000 Configurable Signal Conditioning Solution Data Acquisition and Signal Conditioning BNC-2121 (See Figure 1) CA-1000 (See Figure 2) Configurable signal connectivity solution for connecting counter/timers to different types of standard I/O connectors. You can also incorporate switches and LED indicators. You can place the CA-1000 under a laptop PC, on a benchtop, or in a 19 in. rack. CA-1000 ......................................................................................................See page 351 Dimensions – 30.7 by 25.4 by 4.3 cm (12.1 by 10 by 1.7 in.) PCI-6601, PCI-6602 Accessories BNC-2121, CA-1000, SCB-68, TBX-68, CB-68LP, and CB-68LPR TB-2715 Cables – R6868 or SH68-68-D1 N/A Table 1. Accessories and Cables for PXI-6601 and PCI-6602 PXI-6602, PXI-6608 Accessories BNC-2121, CA-1000, SCB-68, TBX-68, CB-68LP, and CB-68LPR TB-2715 Cables – R6868 or SH68-68-D1 Connects directly to the device Table 2. Accessories and Cables for PXI-6602 and PXI-6608 Accessory BNC-2121 CA-1000 SCB-68 TB-2715 TBX-68 CB-68LP CB-68LPR Description BNC connector block with built-in test features Configurable connector accessory Shielded screw connector block Front-mount terminal block for PXI-660x DIN-rail connector block Low-cost screw connector block Low-cost screw connector block Table 3. Overview of Accessories 390 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com Page 390 390 391 391 391 391 391 Counter/Timer Accessories and Cables Shielded I/O connector block for easy connection of I/O signals to the counter/timer devices. The screw terminals are housed in a metal enclosure for protection from noise corruption. Combined with a shielded cable, the SCB-68 provides rugged, very low-noise signal termination. The SCB-68 also includes two general-purpose breadboard areas. SCB-68 ..............................................................................................................776844-01 Dimensions – 19.5 by 15.2 by 4.5 cm (7.7 by 6.0 by 1.8 in) Figure 3. SCB-68 Shielded I/O Connector Block TB-2715 Terminal Block (See Figure 4) With the TB-2715 terminal block for PXI counter/timer devices, you can connect signals directly without additional cables. Screw terminals provide easy connection of I/O signals. The TB-2715 latches to the front of your PXI module with locking screws and provides strain relief. TB-2715 ............................................................................................................778242-01 Dimensions – 8.43 by 10.41 by 2.03 cm (3.32 by 4.1 by 0.8 in.) Counter/Timer Accessories and Cables SCB-68 Shielded I/O Connector Block (See Figure 3) TBX-68 I/O Connector Block with DIN-Rail Mounting (See Figure 5) Figure 4. TB-2715 I/O Terminal Block CB-68LP and CB-68LPR I/O Connector Blocks (See Figure 6) Low-cost termination accessories with 68 screw terminals for easy connection of field I/O signals to the counter/timer devices. The connector blocks include standoffs for use on a desktop or mounting in a custom panel. The CB-68LP has a vertically mounted 68-pin connector. The CB-68LPR has a right-angle mounted connector for use with with the CA-1000. CB-68LP ............................................................................................................777145-01 Dimensions – 14.35 by 10.74 cm (5.65 by 4.23 in.) CB-68LPR ........................................................................................................777145-02 Dimensions – 7.62 by 16.19 cm (3.00 by 6.36 in.) Figure 5. TBX-68 I/O Connector Block Data Acquisition and Signal Conditioning Termination accessory with 68 screw terminals for easy connection of field I/O signals to the counter/timer devices. The TBX-68 is mounted in a protective plastic base with hardware for mounting on a standard DIN rail. TBX-68 ..............................................................................................................777141-01 Dimensions – 12.50 by 10.74 cm (4.92 by 4.23 in.) Figure 6. CB-68LP and CB-68LPR I/O Connector Blocks National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 391 Counter/Timer Accessories and Cables Counter/Timer Accessories and Cables Cables RTSI Bus Cables (See Figures 7 and 8) Figure 7. RTSI Bus Cable Use RTSI bus cables to connect timing and synchronization signals among measurement, vision, motion, and CAN boards for PCI. For systems using long and short boards, order the extended RTSI cable. 2 boards ..........................................................................................................776249-02 3 boards ..........................................................................................................776249-03 4 boards ..........................................................................................................776249-04 5 boards ..........................................................................................................776249-05 Extended, 5 boards ........................................................................................777562-05 SH68-68-D1 Shielded Cable (See Figure 9) Shielded 68-conductor cable terminated with two 68-pin female 0.050 series D-type connectors. This cable connects counter/timer devices to accessories. 1 m ..................................................................................................................183432-01 2 m ..................................................................................................................183432-02 R6868 Ribbon I/O Cable (See Figure 10) Data Acquisition and Signal Conditioning Figure 8. Extended RTSI Bus Cable 68-conductor flat ribbon cable terminated with two 68-pin connectors. Use this cable to connect the NI PCI-6601 to an accessory. For signal integrity with highfrequency signals, use the SH68-68-D1 with the NI 6602 and NI 6608. 1 m ..................................................................................................................182482-01 Custom Connectivity Components 68-Pin Custom Cable Connector/Backshell Kit (See Figure 11) 68-pin female mating custom cable kit for use in making custom 68-conductor cables. Solder-cup contacts are available for soldering of cable wires to the connector. 68-pin custom cable kit ................................................................................776832-01 Figure 9. SH68-68-D1 Shielded Cable PCB Mounting Connectors Printed circuit board (PCB) connectors for use in building custom accessories that connect to 68-conductor shielded and ribbon cables. Two connectors are available, one for right-angle and one for vertical mounting onto a PCB. 68-pin, male, right-angle mounting..............................................................777600-01 68-pin, male, vertical mounting ....................................................................777601-01 Figure 10. R6868 Ribbon I/O Cable Figure 11. 68-Pin Custom Cable Kit 392 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com Counter/Timer Specifications These specifications are typical for 25 °C unless otherwise noted. Timing I/O DMA channels NI 6601 ...................................................... 1 NI 6602/6608............................................. 3 General-Purpose Up/Down Counter/Timers Number of channels NI 6601 ...................................................... NI 6602/6608............................................. Counter size/number of bits............................. Prescalers (per counter) ................................... 4 up/down counters 8 up/down counters 32 bits 3 bits (divided by 8) 1 bit (divided by 2) Oven-Controlled Crystal Oscillator (OCXO) (NI 6608 Only) Disabled (by default) Power-on state ................................................. Input (high-Z), pulled low Pull down current: 10 µA (min) to 200 µA (max) Hysteresis......................................................... 300 mV Schmitt triggers Compatibility .................................................... 5 V TTL/CMOS Digital logic levels Level Input low voltage Input high voltage Output low voltage (Iout = 4 mA) Output high voltage (Iout = 4 mA) Minimum -0.3 V 2.0 V – 2.4 V Maximum 0.8 V 5.25 V 0.4 V – With Prescaling 60 MHz 125 MHz 125 MHz Minimum source pulse duration With prescalers ......................................... 3.5 ns; edge-detect mode Without prescalers .................................... 5 ns; edge-detect mode Minimum gate pulse duration.......................... 5 ns; edge-detect mode Frequency ranges to measure or generate ≤ 0.005 ppm ≤ 0.005 ppm ≤ 0.00045 ppm/day ≤ 0.045 ppm/year Allowed frequency adjustment........................ 0.5 ppm, typical Digital I/O Number of channels......................................... Compatibility .................................................... Power-on state ................................................. Pulldown current .............................................. Hysteresis......................................................... Data transfers .................................................. Up to 32 input/output 5 V TTL/CMOS Input (high-Z), pulled low 10 µA (min) to 200 µA (max) 300 mV Schmitt triggers Unstrobed I/O Digital logic levels Level Input low voltage Input high voltage Output low voltage (Iout = 4 mA) Output high voltage (Iout = 4 mA) Minimum -0.3 V 2.0 V – 2.4 V Maximum 0.8 V 5.25 V 0.4 V – RTSI Bus (PCI Only) Trigger lines...................................................... 7 Minimum pulse width for trigger and clock .................................. 25 ns PXI Trigger Bus (PXI Only) Trigger lines...................................................... 6 Star trigger ....................................................... 1 Bus Interface Data Transfers Family NI 6601 NI 6602 NI 6608 5 minutes Data Acquisition and Signal Conditioning Without Prescaling 20 MHz 80 MHz 80 MHz 10 MHz ±0.0000075% (75 ppb) Note: You can use the OCXO to replace the PXI 10 MHz backplane clock when the PXI-6608 is installed in the PXI star trigger slot (Slot 2). You can also use it as the counter source or gate in any slot. Base clocks available NI 6601 ...................................................... 100 kHz and 20 MHz NI 6602/6608............................................. 100 kHz, 20 MHz, and 80 MHz Base clock accuracy (NI 6601 and NI 6602) .... ±0.005% (50 ppm)1 Base clock (OCXO) accuracy (NI 6608)............. ±0.0000075% (75 ppb) Maximum source frequency External source selections ............................... I/O connector, RTSI/PXI Trigger lines, software selectable External gate selections................................... I/O connector, RTSI/PXI Trigger lines, software selectable 1 If a PXI-6608 is installed in slot 2 of a PXI chassis, then the PXI-6608 and any PXI-6602 installed in that chassis inherit a base clock accuracy of ±0.0000075% (75 ppb). Family NI 6601 NI 6602 NI 6608 Frequency ......................................................... OCXO accuracy ................................................. Warm-up time (to within 0.02 ppm of operating frequency) ............................. Frequency stability versus supply voltage change (±5%) .................... Temperature stability (0 to 50 °C).................... Drift in frequency ............................................. Counter/Timer Specifications Specifications Frequency to Measure 20 MHz 80 MHz 80 MHz Min/Max Frequency to Generate 10 MHz 40 MHz 40 MHz For more information, please visit ni.com/info and enter exatzz. Transfer modes................................................. DMA, interrupts, programmed I/O PCI, PXI ............................................................. Master, slave Power Requirements Device NI 6601 NI 6602 NI 6608 +5 VDC (±5%)* 0.4 to 0.75 A 0.5 to 1.5 A 1 to 2.5 A Power Available at I/O Connector +4.65 to +5.25 VDC, 1 A +4.65 to +5.25 VDC, 1 A +4.65 to +5.25 VDC, 1 A *Excludes power consumed through I/O connector Transfer rates DMA1,2 Finite Operation Buffer Size (S) Rate (MS/s) 100 5.0 1,000 4.2 10,000 2.0 100,000 1.8 1Values Interrupt1,3 Finite Operation Buffer Size (S) Rate (kS/s) 100 55 1,000 49 10,000 49 100,000 48 may vary depending on your computer hardware, operating system and system activity. Benchmark data was determined on a Pentium II 400 MHz computer with 64 MB RAM running Windows 98 and LabVIEW using one counter of a PCI-6602. 2The number of Physical Dimensions (not including connectors) PCI.............................................................. 17.5 by 9.9 cm (6.9 by 3.9 in.) PXI.............................................................. 16.0 by 10.0 cm (6.3 by 3.9 in.) I/O connector.................................................... 68-pin male SCSI-II type Environment Operating temperature..................................... 0 to 50 °C Storage temperature ........................................ -20 to 70 °C Relative humidity ............................................. 10 to 90%, noncondensing simultaneous DMA transfers you can perform is equivalent to the DMA channels available on your device. 3The rate is based on one counter using the interrupts. If multiple counters share interrupts, the transfer rate per counter is lower. Continuous Operation Buffer Size (MS) Rate (kS/s) 50 28 Certifications and Compliances CE Mark Compliance Continuous Operation Buffer Size (kS) Rate (kS/s) 50 15 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 393 Data Acquisition and Signal Conditioning Counter/Timer Overview Counter/Timer Overview You can use the versatile National Instruments counter/timer devices to create a wide variety of measurement solutions, including measuring a number of time-related quantities, counting events or totalizing, and monitoring position with quadrature encoders. You can also use counter/timers to generate pulses and pulse trains. Counter/timers often fulfill critical timing functions as components of complex measurement systems. The NI 660x counter/timers use the NI-TIO, a National Instruments ASIC chip specifically designed to meet the counting and timing requirements of measurement applications that are beyond the capabilities of off-the-shelf components. The wider functionality and simple programming interface make the NI 660x your best choice for counting and timing applications. Example applications include frequency measurement, position measurement, generation of retriggerable pulses, frequency shiftkeying, two-signal edge separation measurements, continuous buffered event counting, and continuous buffered pulse train measurements. The NI 660x counter/timer devices are readily integrated into measurement systems that require synchronization across multiple hardware devices because they are equipped with the National Instruments PXI trigger bus or the RTSI bus. See the counter/timer tutorial on page 789 for more information. In addition to counter/timer functionality, the NI 660x products include TTL/CMOS-compatible digital I/O ports that are bit configurable for input or output. Counter/Timer Size or Number of Bits The counter size or number of bits indicates how high a counter can count. For example, a 32-bit counter can count up to 232-1 or 4,294,967,295 before it rolls over. A high number of bits is beneficial in cases such as pulse width measurements where a wide dynamic range is required. For example, if you measure pulse widths with a 12.5 ns resolution (80 MHz timebase) using a counter/timer with 32 bits, you can measure pulse widths up to 53 s [(232-1) x 12.5 ns)] with 12.5 ns resolution. Maximum Source Frequency Counter/Timer Considerations Number of Counter/Timers The counter/timer is a basic unit of hardware functionality on a measurement device. The more counter/timers there are on a device, the more counting/timing operations that device can simultaneously perform. The number of DMA channels determines how many buffered, high-speed operations can be simultaneously performed. See page 393 for more information. Family NI 6601 NI 6602 NI 6608 Bus PCI PCI PXI PXI Counter/ Timers 4 8 8 Size 32 bits 32 bits Max Source Frequency 20 MHz1 80 MHz1 Compatibility 5 V TTL/CMOS 5 V TTL/CMOS 32 bits 80 MHz1 5 V TTL/CMOS Maximum source frequency represents the speed of the fastest signal the counter can count. If you use a higher source frequency, you can achieve higher resolution. For example, an 80 MHz counter can count pulses that are 12.5 ns (1⁄80 x 10 ) apart. You can use prescalers to increase the maximum source frequency for event counting and frequency measurement. 6 Digital I/O Up to 32 Up to 32 Pulse Generation ✓ ✓ Buffered Operations ✓ ✓ Up to 32 ✓ ✓ 1Max Debouncing/ Glitch Oscillator Removal Stability ✓ 50 ppm ✓ 50 ppm ✓ 75 ppb GPS Synchr. – – ✓ Buffered Operations2 DMA Interrupt 1 3 3 5 3 Source Frequency with prescalers is 60 MHz for the NI 6601 and 125 MHz for the NI 6602 and NI 6608. These frequencies are dependent on drive strength of input signal and cable length. Consider these speeds to be the maximum. 2DMA transfers have higher throughput than interrupt transfers. See page 393 for detailed specifications. 386 National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 5 Page 388 388 388 Counter/Timer Overview Signal compatibility indicates the signal levels a counter/timer can measure or output, such as TTL/CMOS. Buffered Operations and DMA Timebase Stability Timebase stability can be important when you need to make highquality measurements. Crystal oscillators typically form the basis of electrical circuits used to drive timing of a measurement application. In an ideal case, the oscillation frequency would be constant, but in reality, many factors influence the the behavior of an oscillator. A commonly used measure of quality for an oscillator is stability. Start of Measurement Debouncing and Glitch Removal Noisy signals containing glitches and/or bouncing effects pose special challenges for some counter/timer measurements. Noise may be introduced in the source of the signal, such as with electromechanical relays, or in the connection if there are strong sources of interference in the vicinity of the system. NI 660x devices contain programmable digital filters that eliminate measurement errors caused by spurious spikes and bouncing. Figure 2 shows an example of digital filtering. Calibration Calibration is a key component of any measurement solution. In the case of counter/timers, timebase calibration ensures that the frequency and time measurements are accurate. Calibration certificates enclosed with the National Instruments counter/timers and periodic calibration satisfy your ISO-9000 requirements, certifying that your instrument has been properly calibrated. See page 21 for more information. Data Acquisition and Signal Conditioning The National Instruments counter/timers can capture numerous data points without dead times. These types of measurements, called buffered operations, are valuable in applications that range from statistical analysis on production lines to experiments in molecular chemistry. For instance, when you configure a counter for buffered period measurement, data is moved from the counter into a buffer. Each edge that initiates a measurement also causes a transfer of the count into the buffer, as shown in Figure 1. With buffered operations, data is transferred to the computer memory using DMA or interrupts. DMA offers a considerable performance advantage; if your application requires this performance simultaneously on multiple counter/timers, you must know how many DMA channels are available on a particular counter/timer device. For example, if a device contains three DMA channels and eight counter/timers, you can simultaneously perform three high-speed and five lowerspeed, interrupt-based, buffered operations. On NI 660x devices, National Instruments implements DMA with the NI MITE chip, which is optimized for measurement applications. Units used for stability are typically parts per million (ppm) and parts per billion (ppb). For example, the frequency of a 10 MHz oscillator with 10 ppm stability can be 10 MHz ± 100 Hz; with 100 ppb stability it can be 10 MHz ± 1 Hz. The best technique for improving oscillator stability is to precisely control its temperature as is done in an oven-controlled crystal oscillator (OCXO). The PXI-6608 features such an oscillator. Counter/Timer Overview Signal Compatibility Input Filtered Output T1 T2 T3 Figure 2. Debouncing and Glitch Removal T4 Input Signal T1 T1 T1 T1 T2 T2 T2 T3 T3 Measurement Data Buffer T4 Figure 1. Buffered Period Measurement with Counter/Timers National Instruments • Tel: (800) 433-3488 • Fax: (512) 683-9300 • [email protected] • ni.com 387