Keysight vs Rigol DMM: Switching SCPI Commands

import pyvisa

class DMM:
    """Vendor-agnostic DMM interface."""

    def __init__(self, resource_string: str):
        rm = pyvisa.ResourceManager()
        self._inst = rm.open_resource(resource_string)
        self._inst.timeout = 10000
        idn = self._inst.query('*IDN?').strip()
        print(f'Connected: {idn}')
        # Detect vendor from IDN string
        self._is_rigol = 'RIGOL' in idn.upper()

    def measure_dc_voltage(self, range_v: float = 0) -> float:
        """Measure DC voltage. range_v=0 means auto-range."""
        if range_v:
            return float(self._inst.query(f':MEAS:VOLT:DC? {range_v}'))
        return float(self._inst.query(':MEAS:VOLT:DC?'))

    def measure_ac_voltage(self, range_v: float = 0) -> float:
        """Measure AC voltage (Vrms)."""
        if range_v:
            return float(self._inst.query(f':MEAS:VOLT:AC? {range_v}'))
        return float(self._inst.query(':MEAS:VOLT:AC?'))

    def measure_resistance(self, four_wire: bool = False) -> float:
        """Measure resistance (2-wire or 4-wire)."""
        cmd = ':MEAS:FRES?' if four_wire else ':MEAS:RES?'
        return float(self._inst.query(cmd))

    def set_nplc(self, nplc: float):
        """Set integration time in power line cycles."""
        self._inst.write(f':VOLT:DC:NPLC {nplc}')

    def display_text(self, text: str):
        """Show a message on the front panel display."""
        if self._is_rigol:
            self._inst.write(f':DISP:TEXT:DATA "{text}"')
        else:
            self._inst.write(f':DISP:TEXT "{text}"')

    def get_stats(self) -> dict:
        """Return mean and standard deviation of the reading buffer."""
        if self._is_rigol:
            mean = float(self._inst.query(':STAT:AVER?'))
            sdev = float(self._inst.query(':STAT:SDEV?'))
        else:
            mean = float(self._inst.query(':CALC:AVER:AVER?'))
            sdev = float(self._inst.query(':CALC:AVER:SDEV?'))
        return {'mean': mean, 'sdev': sdev}

    def reset(self):
        self._inst.write('*RST')
        self._inst.query('*OPC?')

    def close(self):
        self._inst.close()

# Works with either instrument — just change the address
dmm = DMM('TCPIP0::192.168.1.11::hislip0::INSTR')   # Keysight 34461A
# dmm = DMM('TCPIP0::192.168.1.12::inst0::INSTR')   # Rigol DM3068

v = dmm.measure_dc_voltage()
print(f'DC voltage: {v:.5f} V')

dmm.display_text('TEST RUNNING')
dmm.close()

import pyvisa
import csv

# ---- Adapter (paste the DMM class from above here, or import it) ----

# ---- Test configuration ----
DMM_ADDR = 'TCPIP0::192.168.1.11::hislip0::INSTR'  # Keysight or Rigol
PSU_ADDR = 'USB0::0x2A8D::0x1602::MY12345::INSTR'

TEST_VOLTAGES = [1.0, 2.0, 3.3, 5.0, 10.0, 12.0]   # V

# ---- Main ----
rm  = pyvisa.ResourceManager()
psu = rm.open_resource(PSU_ADDR)
psu.timeout = 10000
dmm = DMM(DMM_ADDR)

try:
    psu.write('*RST')
    psu.query('*OPC?')
    psu.write(':CURR 0.1')    # 100 mA current limit
    psu.write(':OUTP ON')
    dmm.set_nplc(10)          # slow but accurate: 10 PLC

    rows = []
    for setpoint in TEST_VOLTAGES:
        psu.write(f':VOLT {setpoint}')
        psu.query('*OPC?')

        measured = dmm.measure_dc_voltage()
        error_pct = (measured - setpoint) / setpoint * 100
        rows.append({'setpoint_v': setpoint,
                     'measured_v': measured,
                     'error_pct':  error_pct})
        print(f'Set {setpoint:5.1f} V  →  Measured {measured:.5f} V  '
              f'({error_pct:+.3f}%)')

    with open('dc_accuracy.csv', 'w', newline='') as f:
        w = csv.DictWriter(f, fieldnames=['setpoint_v', 'measured_v', 'error_pct'])
        w.writeheader()
        w.writerows(rows)
    print('\nSaved: dc_accuracy.csv')

finally:
    psu.write(':OUTP OFF')
    psu.close()
    dmm.close()
    rm.close()