PCI-6601 4-Channel 32-Bit Counter/Timer Device
The NI PCI-6601 is a dedicated counter/timer and digital I/O device designed for event counting, frequency measurement, pulse generation, encoder monitoring and timing control.
It provides four independent 32-bit counter/timers with a maximum unprescaled source frequency of 20 MHz. Prescaling can support higher-frequency input signals in compatible measurement modes.
Up to 32 individually configurable TTL/CMOS digital I/O lines provide flexible access to counter gates, sources, outputs and general-purpose digital signals.
Key Features of the PCI-6601
- Four independent 32-bit counter/timers
- 20 MHz maximum unprescaled source frequency
- Higher-frequency measurements using supported prescalers
- Up to 32 digital I/O lines
- 5 V TTL/CMOS-compatible digital signaling
- Event and edge counting
- Frequency and period measurement
- Pulse-width and semi-period measurement
- Two-edge separation measurement
- Quadrature encoder measurement
- Pulse and pulse-train generation
- One high-speed DMA channel
- RTSI synchronization support
- 68-pin female SCSI-II connector
- Conventional PCI interface
PCI-6601 Technical Specifications
| Product Model | PCI-6601 |
|---|---|
| Part Number | 777918-01 |
| Product Type | Counter/timer and digital I/O device |
| Bus Interface | Conventional PCI |
| Counter/Timers | 4 |
| Counter Resolution | 32 bits |
| Maximum Source Frequency | 20 MHz without prescaling |
| Timebase Resolution | 50 ns using the 20 MHz timebase |
| Digital I/O | Up to 32 individually configurable lines |
| Logic Compatibility | 5 V TTL/CMOS |
| DMA Resources | One high-speed DMA channel |
| Synchronization | RTSI trigger-bus support |
| Front Connector | 68-pin female SCSI-II |
| Driver Software | NI-DAQmx or supported legacy NI software |
| Lifecycle | Legacy counter/timer device |
PCI-6601 Part Number and Accessories
| Item | Part Number | Description |
|---|---|---|
| PCI-6601 | 777918-01 | Four-channel, 32-bit PCI counter/timer device |
| SH68-68-D1 Cable | 183432-01 or 183432-02 | Shielded 68-pin digital I/O cable; part number depends on length |
| SCB-68A | 782536-01 | Shielded 68-pin screw-terminal connector block |
| CB-68LP | 777145-01 | General-purpose 68-pin terminal block |
| RTSI Cable | System dependent | Shares timing and trigger signals between compatible PCI devices |
The PCI-6601 uses a 68-pin female SCSI-II connector rather than the VHDCI connector found on many later M Series boards. Confirm the cable connector before ordering.
Four Independent Counters
Each 32-bit counter can measure or generate a timing signal independently. Multiple counters can also be combined for more complex measurements and synchronized pulse operations.
The 32-bit resolution supports long measurement intervals and large event counts without frequent rollover.
Frequency and Period Measurement
The PCI-6601 can measure signal frequency, period, pulse width, semi-period and the separation between two edges. Measurement accuracy depends on the selected timebase and input-signal quality.
The maximum unprescaled source frequency is 20 MHz. Supported prescaling modes can extend the measurable input frequency when individual input edges do not need to be resolved directly.
Quadrature Encoder Measurement
The counters can monitor quadrature encoder signals for position and direction measurement. Appropriate A, B and index connections must be wired to compatible counter input terminals.
Industrial encoders using differential or higher-voltage signals require external receivers or isolation hardware.
Pulse and Pulse-Train Generation
The PCI-6601 can generate single pulses, continuous pulse trains and frequency-divided outputs. These functions are useful for device clocks, test triggers and step/direction control signals.
Digital I/O Capability
Up to 32 digital lines can be used for counter signals or general-purpose digital I/O. Lines are compatible with 5 V TTL/CMOS logic and should not directly drive high-current loads.
DMA and RTSI Synchronization
One DMA channel supports high-speed buffered counter operations. When multiple buffered tasks compete for the DMA resource, some operations may need interrupt-based transfers.
The RTSI bus allows timing signals to be shared with other compatible PCI devices installed in the same computer.
PCI-6601 Applications
- Event and edge counting
- Frequency measurement
- Period and pulse-width measurement
- Quadrature encoder monitoring
- Rotational speed measurement
- Pulse-train generation
- Frequency division
- Automated test timing
- Digital control and monitoring
- Machine position measurement
- Photon and detector pulse counting
Encoder and Motion Feedback
The PCI-6601 can monitor incremental encoder signals to calculate position, direction and speed. Signal conditioning should be selected according to encoder output type and cable length.
Automated Timing Systems
Generated pulses can trigger instruments, sequence test fixtures or provide a programmable clock to a DUT.
Event Counting
The 32-bit counters can count pulses produced by sensors, switches, detectors and electronic systems. Clean digital edges are essential for reliable counting.
PCI-6601 Installation Workflow
Step 1: Verify the PCI Slot
Confirm that the computer contains a compatible conventional PCI expansion slot.
Step 2: Confirm Driver Compatibility
Check the operating system and supported NI-DAQmx or legacy driver version.
Step 3: Install the Board
Power down the computer, observe ESD precautions and secure the PCI-6601.
Step 4: Connect the 68-Pin Cable
Use a compatible SCSI-II cable such as the SH68-68-D1 and verify the terminal pinout.
Step 5: Test the Counters
Use NI MAX or a simple application to count a known TTL pulse source.
Step 6: Validate Signal Integrity
Check logic thresholds, grounding, edge quality, shielding and the selected counter source.
PCI-6601 Troubleshooting
The counter records more pulses than expected
Noisy or slowly transitioning signals can produce false edges. Improve shielding or add a Schmitt-trigger buffer.
The counter remains at zero
Verify the physical source terminal, signal amplitude, ground reference and selected active edge.
Frequency measurement is unstable
Increase the measurement interval and check the input signal for jitter, noise or missing pulses.
A buffered counter task reports a DMA conflict
The PCI-6601 has one DMA channel. Reconfigure one task to use interrupts or change the task architecture.
The device is not detected
Check board seating, PCI compatibility and the installed NI driver version.
PCI-6601 Comparison
| Model | Counters | Resolution | Maximum Source Frequency | Best Suited For |
|---|---|---|---|---|
| PCI-6601 | 4 | 32-bit | 20 MHz | General counter/timer applications |
| PCI-6602 | 8 | 32-bit | 80 MHz | Higher counter density and speed |
| PCI-6624 | 8 | 32-bit | Higher-performance timing | Advanced counter applications |
| PCIe-6612 | 8 | 32-bit | High-speed PCI Express timing | Newer PCIe systems |
PCI-6601 vs PCI-6602
The PCI-6601 provides four counters with a 20 MHz maximum unprescaled source frequency. The PCI-6602 provides eight counters and higher timing performance.
PCI-6601 vs PCIe-6612
The PCIe-6612 uses PCI Express and provides more counters with newer timing capabilities. Migration requires verification of connector pinout, timing behavior and software.
Why Choose the PCI-6601?
Choose the PCI-6601 for maintaining conventional PCI systems that require four dedicated counters, extensive TTL digital connectivity and NI-compatible timing functions.
PCI-6601 Frequently Asked Questions
What is the PCI-6601 part number?
The standard part number is 777918-01.
How many counters does it provide?
The PCI-6601 provides four independent 32-bit counter/timers.
What is the maximum input frequency?
The maximum unprescaled source frequency is 20 MHz.
Can it measure an encoder?
Yes. It supports quadrature encoder position and direction measurement.
Which cable is commonly used?
The SH68-68-D1 shielded digital cable is a common connection option.
Does it measure analog voltage?
No. The PCI-6601 is a counter/timer and digital I/O device rather than an analog DAQ board.
Recommended Related Products
- PCI-6602 Counter/Timer Device
- PCI-6624 Counter/Timer Device
- PCIe-6612 Counter/Timer Device
- View More NI Data Acquisition Products
Request a Quote for the PCI-6601
Contact us for current availability and pricing for the NI PCI-6601 Counter/Timer Device. We can also help identify compatible SH68-68-D1 cables, connector blocks and newer PCI Express timing devices.
