PCI-6704 32-Channel Static Voltage and Current Output Device
The PCI-6704 is a high-density static analog output device for software-timed voltage and current control. It provides 16 independent 16-bit voltage outputs and 16 independent 16-bit current-source outputs.
Voltage channels support bipolar output across approximately ±10 V. Current channels can source between approximately 0.1 mA and 20 mA without requiring an external loop-excitation supply, subject to the specified compliance-voltage limits.
The device also includes eight bidirectional 5 V TTL/CMOS digital I/O lines. Its combination of voltage and current outputs makes it suitable for process-control simulation, valve control, calibration systems and automated testing of industrial analog inputs.
Key Features of the PCI-6704
- 16 independent analog voltage outputs
- 16 independent analog current outputs
- 32 total analog output channels
- 16-bit analog output resolution
- Approximately ±10 V voltage output range
- Approximately 0.1 mA to 20.2 mA current output range
- Current-source outputs require no external loop excitation
- 0 V to 10 V current-output compliance range
- Software-timed static operation
- Independent programmable power-up states
- Eight bidirectional TTL/CMOS digital I/O lines
- NI-DAQmx software support
PCI-6704 Technical Specifications
| Product Model | PCI-6704 |
|---|---|
| Part Numbers | 777306-01 / 183689-01 |
| Product Type | Static Voltage and Current Output Device |
| Bus Interface | PCI |
| Total Analog Outputs | 32 |
| Voltage Output Channels | 16 |
| Current Output Channels | 16 |
| Output Resolution | 16 bits |
| Voltage Output Range | ±10.1 V |
| Voltage Output Drive | ±10 mA maximum |
| Current Output Range | 0.1 mA to 20.2 mA |
| Current Output Type | Source |
| Current Output Compliance | 0 V to 10 V |
| Update Mode | Software timed, static |
| Digital I/O | 8 bidirectional lines |
| Digital Logic | 5 V TTL/CMOS |
| Power-Up States | Independent, user programmable |
| Front Connector | 68-pin male SCSI-II type |
| Operating Temperature | 0°C to 55°C |
| Software Driver | NI-DAQmx |
PCI-6704 Part Number and Accessories
| Item | Part Number | Description |
|---|---|---|
| PCI-6704 | 777306-01 / 183689-01 | 16-voltage-output and 16-current-output PCI device |
| SH68-68-D1 Cable, 1 m | 183432-01 | Shielded cable designed for NI 670x analog output devices |
| SH68-68-D1 Cable, 2 m | 183432-02 | Two-meter shielded NI 670x connection cable |
| SCB-68 | 776844-01 | Shielded screw-terminal connector block |
| CB-68LP | 777145-01 | Low-profile 68-position terminal block |
| CB-68LPR | 777145-02 | Right-angle 68-position terminal block |
| R6868 Cable, 1 m | 182482-01 | Unshielded ribbon cable for compatible terminal accessories |
Sixteen Voltage Outputs
The PCI-6704 provides the same 16 bipolar voltage-output channels as the PCI-6703. Every channel can maintain an independent static voltage setpoint.
Voltage outputs are appropriate for command references, electronic biasing, sensor simulation and equipment that accepts a ±10 V control signal.
Sixteen Current-Source Outputs
The additional current channels allow the device to simulate or control current-loop equipment. Each channel sources current up to approximately 20 mA and does not require a separate external excitation supply.
The current outputs source but do not sink current. Load resistance and wiring voltage drop must remain within the 0 V to 10 V compliance range.
Testing 4–20 mA Equipment
The PCI-6704 is useful for stimulating industrial controllers, data acquisition systems and input modules designed for current-loop signals.
Software can program multiple current levels to verify scaling, alarm thresholds, fault responses and control-system accuracy. The complete loop should be checked for compliance voltage before testing.
Independent Power-Up States
Every analog output can use a defined power-up state. This helps place the test fixture or control system into known voltage and current conditions when the computer starts.
Startup states should be selected conservatively when outputs connect to active control equipment.
Software-Timed Output Architecture
The PCI-6704 is designed for stable setpoints and relatively slow control changes. It does not provide the sample-clocked waveform generation capabilities of the PCI-6722 or PCI-6733.
Applications should allow sufficient settling time after changing a channel before making a precision measurement.
PCI-6704 Applications
- 4–20 mA current-loop simulation
- Industrial controller input testing
- Process-control signal generation
- Valve and actuator setpoint control
- PLC analog input validation
- Multichannel voltage generation
- Sensor-transmitter simulation
- Calibration systems
- Automated production testing
- Laboratory process simulation
PCI-6704 Installation Workflow
Step 1: Identify Voltage and Current Loads
Document which fixture connections require ±10 V signals and which require sourced current.
Step 2: Calculate Current-Loop Compliance
Calculate voltage drop across the load and wiring at the maximum programmed current. Keep the total within the specified compliance range.
Step 3: Install NI-DAQmx
Install a driver release compatible with the PCI-6704 and operating system.
Step 4: Install the Board
Power down the computer, follow ESD precautions and install the PCI-6704 securely.
Step 5: Connect the SH68-68-D1 Cable
Connect the recommended cable and terminal block, then verify voltage-channel, current-channel and ground assignments.
Step 6: Configure Safe Power-Up States
Program conservative default values before connecting the DUT or industrial controller.
Step 7: Validate the Outputs
Measure voltage channels with a DMM and verify current channels using an appropriate loop load or current measurement circuit.
PCI-6704 Troubleshooting
A current output cannot reach 20 mA
Check the load resistance and cable voltage drop. The current channel may be outside its compliance-voltage range.
The current reading is close to zero
Verify loop continuity, polarity and return wiring. The PCI-6704 sources current and requires a complete current path.
A voltage channel changes when a current channel operates
Review shared return wiring and cable resistance. Separate or improve ground paths where the fixture design permits.
The outputs change too slowly for the application
The PCI-6704 is a static software-timed device. Select a hardware-timed analog output board when rapid waveform updates are required.
Outputs initialize at incorrect values
Review the programmed power-up states and confirm that the configuration is associated with the correct serial-numbered device.
PCI-6704 Comparison
| Model | Voltage Outputs | Current Outputs | Resolution | Best Suited For |
|---|---|---|---|---|
| PCI-6704 | 16 | 16 | 16-bit | Static voltage and current control |
| PCI-6703 | 16 | 0 | 16-bit | Static voltage-only applications |
| PCI-6722 | 8 | 0 | 13-bit | Hardware-timed waveform generation |
| PCI-6733 | 8 | 0 | 16-bit | High-speed precision voltage waveforms |
PCI-6704 vs PCI-6703
Both products provide 16 software-timed, 16-bit voltage outputs and eight digital lines. The PCI-6704 additionally provides 16 independent current-source channels for process-control and current-loop applications.
PCI-6704 vs PCI-6733
The PCI-6704 prioritizes channel count and current-output capability. The PCI-6733 provides fewer channels but supports hardware-timed high-speed voltage waveform generation.
Frequently Asked Questions
How many outputs does the PCI-6704 provide?
It provides 32 analog outputs: 16 voltage channels and 16 current channels.
Can it generate 4–20 mA signals?
Yes. Its current channels can source values covering the commonly used 4–20 mA control range.
Does the current output require an external excitation supply?
No. The PCI-6704 current channels source current internally, provided the load remains within the specified compliance range.
Can the PCI-6704 sink current?
No. Its current channels are source outputs.
Can it generate high-speed waveforms?
No. It is a software-timed static output device intended for DC levels and relatively slow setpoint changes.
What is the standard PCI-6704 part number?
The commonly specified catalog part number is 777306-01. Additional hardware identifiers may also appear on legacy units.
Recommended Related Products
- PCI-6703 16-Channel Voltage Output Device
- PCI-6722 Analog Output Device
- PCI-6731 16-Bit Analog Output Device
- PCI-6733 8-Channel Analog Output Device
- View More NI Analog Output Hardware
Request a Quote for the PCI-6704
Contact us for current availability, condition and pricing for the PCI-6704 32-channel voltage and current output device. We can also supply compatible SH68-68-D1 cables, terminal blocks and alternative NI analog output products.
