Tracking Markers

This Python example, tracking-markers.py, demonstrates using tracking markers. A simulated instrument and waveform is used instead of an oscilloscope. Python 3 supports unicode, so a Greek symbol is shown in output from a print statement.

Example Script

markers-tracking.py

#!python3

"""This program illustrates, in the Infiniium XR8
oscilloscope, using tracking markers.
"""

# Import modules.
import pyvisa
import sys
from matplotlib.ticker import EngFormatter

# Global variables.
oscilloscope_visa_address = "TCPIP0::localhost::hislip0,4880::INSTR"
timeout = 20000  # 20 seconds.
source = "CHANnel1"
eng_s = EngFormatter(unit="s", places=2, sep=" ")
eng_V = EngFormatter(unit="V", places=2, sep=" ")


def exit_program():
    """Exit program."""

    # Close connection to oscilloscope.
    sys.stdout.write("Closing oscilloscope connection.\n")
    Infiniium.write(":SYSTem:GTLocal")  # Unlock GUI.
    Infiniium.clear()  # Clear oscilloscope communications interface.
    Infiniium.close()  # Close communications interface to oscilloscope.
    rm.close()  # Close resource manager.
    print("End of program.")
    sys.exit()


def check_error_queue(when):
    """Check error queue."""

    errors_found = False
    while True:
        # Keep reading errors until "No error".
        error_string = Infiniium.query(":SYSTem:ERRor:NEXT? DIAGnostic")
        if error_string:  # If there is an error string value.

            if error_string.find("0,", 0, 2) == -1:  # Not "No error".
                errors_found = True
                print(f"ERROR: {error_string}")

            else:  # "No error"
                break

        else:  # :SYSTem:ERRor:NEXT? DIAGnostic should always return string.
            errors_found = True
            print("ERROR: :SYSTem:ERRor:NEXT? DIAGnostic returned nothing.")
            break

    if errors_found:
        print(f"Exited because error(s) found when: '{when}'")
        exit_program()


# ==========================================================
# Main program:
# ==========================================================

# Connect and initialize oscilloscope.
rm = pyvisa.ResourceManager("C:\\Windows\\System32\\visa64.dll")
try:
    Infiniium = rm.open_resource(oscilloscope_visa_address)
except Exception:
    print(
        f"Unable to connect to oscilloscope at {oscilloscope_visa_address}. Aborting program."
    )
    sys.exit()

Infiniium.timeout = timeout  # Set global timeout.
Infiniium.clear()  # Clear the instrument bus.
# Lock GUI happens automatically.

# Default Setup.
print("Default Setup.")
Infiniium.write(":SYSTem:DEFault")

# # Use auto-scale to automatically set up oscilloscope.
# print("Autoscale.")
# Infiniium.query(":SYSTem:AUToscale;*OPC?")

# Make a Single acquisition.
Infiniium.query(":ACQuire:SINGle;*OPC?")

# Get times of interest using "time at" measurements.
Infiniium.write(f":MEASure:HORizontal:TMAXimum:SOURce {source}")
qresult = Infiniium.query(":MEASure:HORizontal:TMAXimum:SOURce?").strip()
print(f'Measure horizontal "time at max" source: {qresult}')

Infiniium.write(":MEASure:HORizontal:TMAXimum")
time_at_max = float(Infiniium.query(":MEASure:HORizontal:TMAXimum?"))
print(f'Measured "time at max" on {source}: {eng_s(time_at_max)}')

Infiniium.write(f":MEASure:HORizontal:TMINimum:SOURce {source}")
qresult = Infiniium.query(":MEASure:HORizontal:TMINimum:SOURce?").strip()
print(f'Measure horizontal "time at min" source: {qresult}')

Infiniium.write(":MEASure:HORizontal:TMINimum")
time_at_min = float(Infiniium.query(":MEASure:HORizontal:TMINimum?"))
print(f'Measured "time at min" on {source}: {eng_s(time_at_min)}')

# Place tracking markers at those times.
Infiniium.write(":MARKer:Y1A:STATe TRACk")
Infiniium.write(f":MARKer:X1:SOURce {source}")
Infiniium.write(f":MARKer:X1:POSition {time_at_max}")

Infiniium.write(":MARKer:Y2A:STATe TRACk")
Infiniium.write(f":MARKer:X2:SOURce {source}")
Infiniium.write(f":MARKer:X2:POSition {time_at_min}")

# Get vertical values from tracking markers.
V_at_max = float(Infiniium.query(f":MEASure:MARKer:Y1A?"))
print(f'Tracking marker voltage at "time at max" on {source}: {eng_V(V_at_max)}')
V_at_min = float(Infiniium.query(f":MEASure:MARKer:Y2A?"))
print(f'Tracking marker voltage at "time at min" on {source}: {eng_V(V_at_min)}')
Infiniium.write(":MARKer:REFerence X2")
delta_V = float(Infiniium.query(f":MEASure:MARKer:DY1A?"))
print(f"Voltage delta from tracking markers on {source}: {eng_V(delta_V)}")

# Check error queue.
check_error_queue("End of program")

# Exit program.
exit_program()