In-Field Calibration Procedure for ProDAQ 6150 Thermocouple Instrument

Bustec has introduced a streamlined, in-field calibration and validation procedure for its ProDAQ 6150 Isolated Precision Thermocouple LXI Instrument. This process enables users to calibrate and verify thermocouple measurement accuracy directly on-site, eliminating the need to return equipment to a calibration lab and minimizing system downtime.

The procedure is implemented using Bustec’s proprietary in-field calibration software in conjunction with the Ectron 1140A precision thermocouple and voltage simulator. This system supports full calibration and validation of all ProDAQ 6150 models, including the 6150-AA, 6150-AB, and 6150-AC.

Calibration Methodology

The calibration workflow is divided into two primary stages:

1. Voltage Calibration (VCAL)
   • Ensures accurate thermoelectric voltage measurements at the instrument inputs.
   • Executed using a standard copper (Cu) cable assembly.
   • The Ectron 1140A injects known voltage levels; the ProDAQ 6150 records the response to compute calibration coefficients.
   • These coefficients are then stored directly in the device.
2. Cold Junction Offset Calibration (CJCAL)
   • Calibrates the cold junction compensation for thermocouple inputs.
   • Uses a Type T thermocouple alloy cable assembly, matching the output of the Ectron 1140A to the ProDAQ 6150.
   • The simulator emulates thermal conditions, allowing correction of offset errors in the cold junction reference.

Throughout both phases, the software configures the Ectron simulator automatically. However, the user is responsible for installing the correct cable assembly for each calibration phase. Incorrect cables may introduce error voltages and invalidate results.

Validation Capabilities: Pre- and Post-Calibration

The system supports both Pre-Calibration Validation and Post-Calibration Validation using simulated thermocouple inputs at defined reference temperatures (e.g., 0 °C and 100 °C).

• Pre-Calibration Validation:
  Determines measurement drift since the last calibration cycle. Useful for adjusting recalibration schedules based on actual performance.
• Post-Calibration Validation:
  Verifies the effectiveness of the newly applied calibration coefficients. Results are compared against internal limits, with channels classified as PASS, PASS* (marginal), or FAIL.

Validation requires thermocouple cables made from the same alloy type selected in the software, to ensure accurate simulation and comparison.

Automation and Efficiency

Using Y-cables, the system supports simultaneous calibration and validation across multiple channels—up to the full width of the ProDAQ 6150 (48 channels)—without compromising measurement integrity. This significantly reduces the total test time.

The ProDAQ 6150 Infield Calibration Software features:

• Automated channel prompts and cable layout selection
• Built-in connection validation via VISA interface
• Result logging and certificate export in Excel format

Required Equipment

To perform the in-field calibration, the following components are necessary:

• ProDAQ 6150 Thermocouple Instrument
• Ectron 1140A Thermocouple Simulator
• Copper (Cu) and Type T alloy mini-TC cables
• PC with Bustec VISA library and ProDAQ 6150 driver
• ProDAQ 6150 Infield Calibration Software (standalone executable)

All software and driver packages are available for download from the Bustec Resource Page.

Technical Advantages

This in-field calibration process delivers:

• Improved measurement traceability for thermocouple-based DAQ systems
• Minimal system downtime with no need for external recalibration services
• Consistent accuracy and compliance with ISO 9001 and industry calibration standards

• Compatibility with IEEE 1588 synchronization, maintaining precise timestamp alignment

Download the ProDAQ 6150 Calibration Manual

For a detailed step-by-step guide, refer to the ProDAQ 6150 Calibration User Manual (PDF) which includes connection diagrams, software interface screenshots, and validation result examples.