I. Setting Up and Verifying Status Prior to Calibration
To enable the internal crystal oscillator and analogue circuitry to achieve thermal stability and remove initial discrepancies brought on by temperature drift, turn on the hot runner signal generator and preheat it for at least half an hour.
To verify that there are no hardware issues with any of the channels and that the device is operating normally, navigate to the "System Settings" menu on the device and run a self-test.
To prevent interference from other signals during the calibration process, disable all AM, FM, PM, and other modulation modes and consistently choose a standard sine wave/DC signal as the output waveform.
Preheat the reference equipment and connect a high-precision frequency counter, a multi-channel oscilloscope with a bandwidth of at least 100MHz, and a process signal calibrator with an accuracy class of at least ±0.01%.
II. Recalibration of Frequency Reference
Use a high-precision frequency counter to measure the actual output frequency after setting the signal generator's output frequency to a standard value of 10MHz.
Enter the "Frequency Calibration" option and change the "Frequency Correction Factor" until the deviation is zero if the measured value deviation is greater than ±1 ppm.
In order to ensure that the clock reference accuracy satisfies the requirements, the calibration procedure covers the frequently used 10kHz, 1MHz, 10MHz, and 100MHz frequency ranges for hot runner verification.
III. Recalibration of Output Amplitude
Using an oscilloscope or high-precision multimeter, determine the actual output amplitude after setting the output amplitude to 1Vpp (peak-to-peak value).
To remove the amplitude output error, use the "Amplitude Calibration" option to modify the "Gain Correction Value" if the deviation is greater than ±1%.
For hot runner verification, the calibration includes the widely used amplitude ranges of 10mVpp, 100mVpp, 10Vpp, and 20Vpp. Turn on the oscilloscope's high-impedance input mode (≥1MΩ) for high-amplitude calibration to prevent load effects from causing deviations.
IV. Recalibration Specific to Thermal Signals
Thermocouple Signal Calibration: Configure the signal generator to produce millivolt analogue signals from K-type and J-type thermocouples, which are widely used. To make sure the temperature simulation output accuracy satisfies the hot runner temperature control channel's verification requirements, modify the thermocouple output correction coefficient using the process calibrator's millivolt measurement value as a guide.
To calibrate RTD signals, set the signal generator to produce simulated resistance signals from popular RTDs like Pt100 and Cu50. Make that the simulated resistance output deviation is ≤ ±0.05%FS by adjusting the RTD output correction coefficient using the resistance measurement value from the process calibrator as a benchmark.
V. Synchronous multi-channel recalibration
Using a multi-channel oscilloscope, concurrently obtain the output signals of all slave channels and use the rising edge of the main channel output waveform as a benchmark to determine the phase time difference between each channel and the main channel.
To fine-tune the channel delay correction coefficient until the synchronisation divergence between all channels and the main channel is ≤0.01s, enter the "Delay Calibration" menu for each channel.
Turn on the equipment's cable resistance adjustment feature if the synchronisation trigger line length is more than 200 meters. To counteract the synchronisation deviation brought on by long-distance transmission, automatically compute the transmission delay compensation depending on the cable length and cross-sectional area.
VI. Verification and solidification of parameters after calibration
Once all calibrations are finished, choose ten calibration points at random from the whole range and use a reference device to test each point's output value individually to ensure that the accuracy deviation of each point is within the permitted range.
To ensure that there is no instability brought on by drift over time, run the equipment continuously for 30 minutes while gathering output accuracy and synchronisation deviation data every five minutes.
The equipment's non-volatile memory should be used to store all calibrated frequency correction factors, gain correction values, thermal signal correction factors, and delay correction factors. Following a power loss and restart, these parameters won't be lost.
To create a calibration file that serves as a baseline for future periodic recalibrations, note every parameter value from this calibration.
