NI 6601/6602/6608 Calibration Procedure

Calibration Executive 3.5.2 Help

Edition Date: June 2014

Part Number: 374563A-01

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This topic contains information for calibrating the National Instruments 6601/6602/6608 using Calibration Executive.

Calibration Executive Procedure Features:


Manual Mode

Selectable Test Points


Approximate Test Time: (NI 6601/6602) 1 minute, (NI 6608) 95 minutes


Test Equipment

The following table lists the test equipment required to calibrate NI 6601/6602/6608 devices.

InstrumentRecommended Model Requirements
Highly Stable 10 MHz Clock Source Make sure the clock source outputs a 10 MHz TTL square wave. For the 6601/6602 use a clock source that is accurate to within one ppm. For the NI 6608 use a clock source that is accurate to within 0.75 ppb.
Chassis NI PXI-1042,
NI PXI-1042Q
Use with PXI modules.
DAQ AccessoryNI SCB-68Shielded I/O connector block with 68 screw terminals for easy signal connection to 68- or 100-pin DAQ devices.
Shielded DAQ CableNI Sh68-68-D1You must use this cable for calibrating NI 660x devices.
CompactPCI-to-PCI AdapterYou must use this adapter in a PCI chassis to verify the onboard oscillator on the NI PXI-6602. If you verify the NI PXI-6602 in a PXI chassis, the measured frequency is that of the PXI backplane clock instead of the onboard oscillator.

Test Conditions

The following setup and environmental conditions are required to ensure the NI 6601/6602/6608 meets published specifications.

  • Keep connections to the device as short as possible. Long cables and wires act as antennae, picking up extra noise that can affect measurements.
  • Use shielded coaxial wire for all cable connections to the device.
  • Maintain a temperature of 25 °C.
  • Keep the relative humidity below 80%.
  • Allow a warm-up time of at least 15 minutes to ensure that the measurement circuitry of the NI 660x device and the clock source are at a stable operating temperature.
  • (PXI) Ensure that the PXI chassis fan speed is set to HIGH, that the fan filters are clean, and that the empty slots contain filler panels.

Device Setup

Connecting 6601/6602 Devices to a Clock Source

  1. Install the NI 6601/6602 device as described in the DAQ Getting Started Guide.
  2. Use the NI Sh68-68-D1 cable to connect the NI 6601/6602 device to the NI SCB-68.
  3. Using twisted-pair wires, connect the clock to source pins 7 and 41 on the NI SCB-68. Pin 7 corresponds to PFI_35, which is the SOURCE of counter 1 on all NI 6601/6602 devices. Pin 41 is the digital ground.
  4. Launch the Calibration Executive procedure and complete the setup wizard.

Connecting NI 6608 Devices to a Clock Source

  1. Install the NI 6608 device in as described in the DAQ Quick Start Guide.
  2. The NI 6608 must be installed in slot 2 of the PXI chassis for calibration. Configure the NI 6608 in Measurement & Automation Explorer (MAX) to make sure MAX recognizes the device as being in slot 2:
    1. Launch MAX.
    2. Expand the Devices and Interfaces branch of the MAX configuration tree. PXI system controllers that have not yet been configured appear as PXI System (Unidentified). Right-click PXI System (Unidentified), and select the appropriate controller model from the Identify As menu. For MXI-3 and MXI-4 controllers, select External PC.
    3. Expand the PXI System controller to display a list of chassis.
    4. To identify each chassis, right-click the chassis name, and select the appropriate chassis model from the Identify As menu.
    5. Verify that MAX lists the NI 6608 as being in slot 2.
  3. Use the NI Sh68-68-D1 cable to connect the NI 6608 to the NI SCB-68.
  4. Connect the clock source to pin 2 (PFI_39). PFI_39 is the SOURCE of counter 0 on the NI 6608.
  5. Connect the ground of the clock source to pin 36.
  6. Launch the Calibration Executive procedure and complete the setup wizard.
NOTE icon Note   If the NI 6601/6602/6608 fails after calibration, refer to the Troubleshooting Guidelines. If the NI 6608 fails after troubleshooting, return it to NI for repair or replacement. NI 6601/6602 devices that fail verification cannot be adjusted and must be returned to National Instruments for repair or replacement.

Troubleshooting Guidelines

Use the following troubleshooting guidelines if the NI 6601/6602/6608 device fails after running the calibration procedure:

  1. Verify that the clock source is a 10 MHz TTL signal.
  2. Verify that the device is properly connected, and run the Calibration Executive procedure again.
  3. If the calibration fails after running the Calibration Procedure again, open the test panel in MAX and configure as follows:
    • Counter Mode: Simple Event Counting
    • Counter: GPCTR0
    • Event Source: Counter Source Pin

An increasing Counter value indicates that the device is connected properly. A counter value that does not change indicates that the signal is not connected or is not working.


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