NI NIPCI-6601 32-bit counter/timer Datasheet

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.
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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
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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.)
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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
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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
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Page
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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
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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
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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
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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
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5
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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
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387
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