Multimeter Device - MP730027 Driver

Digital multimeter control library with support for voltage, current, resistance, continuity, and temperature measurements using SCPI protocol over Ethernet.

Device Info

• Model: Multicomp-Pro MP730027
• Type: Digital Multimeter
• Interface: Ethernet (TCP Socket)
• Default Port: 3000
• Protocol: SCPI (Standard Commands for Programmable Instruments)

Installation

The MP730027 driver is part of the multimeter_device package:

from multimeter_device import MP730027

Quick Start

from multimeter_device import MP730027

# Connect to multimeter
mm = MP730027("192.168.1.99", port=3000)

# Measure DC voltage
voltage = mm.measure_dc_voltage()
print(f"DC Voltage: {voltage}V")

# Measure resistance
resistance = mm.measure_resistance()
print(f"Resistance: {resistance}Ω")

# Generic measurement
result = mm.measure("ac_current")
print(f"AC Current: {result['value']}A")

API Reference

Initialization

mm = MP730027(ip, port=3000, timeout=2)

Parameters:

• ip (str): Device IP address
• port (int): TCP port (default: 3000)
• timeout (float): Socket timeout in seconds (default: 2)

Voltage Measurements

measure_dc_voltage() -> str

Measure DC voltage (V).

voltage = mm.measure_dc_voltage()
# Returns: "5.00" (as string)

measure_ac_voltage() -> str

Measure AC voltage (V).

voltage = mm.measure_ac_voltage()
# Returns: "230.5" (as string)

Current Measurements

measure_dc_current() -> str

Measure DC current (A).

current = mm.measure_dc_current()
# Returns: "0.50" (as string)

measure_ac_current() -> str

Measure AC current (A).

current = mm.measure_ac_current()
# Returns: "1.23" (as string)

Resistance & Continuity

measure_resistance() -> str

Measure resistance (Ω).

resistance = mm.measure_resistance()
# Returns: "1500" (as string, in ohms)

measure_continuity() -> str

Test continuity (beeps if resistance < 50Ω).

result = mm.measure_continuity()
# Returns: "0" (beeps) or "1" (open circuit)

Temperature

measure_temperature() -> str

Measure temperature (°C). Requires probe sensor connected.

temp = mm.measure_temperature()
# Returns: "25.3" (as string, in Celsius)

Generic Measurement

measure(mode: str) -> dict

Unified interface for all measurement types.

result = mm.measure("dc_voltage")
# Returns: {"mode": "dc_voltage", "value": "5.00"}

Supported Modes:

• "dc_voltage" - DC voltage measurement
• "ac_voltage" - AC voltage measurement
• "dc_current" - DC current measurement
• "ac_current" - AC current measurement
• "resistance" - Resistance measurement
• "continuity" - Continuity test
• "temperature" - Temperature measurement

Returns:

{
    "mode": str,      # The measurement mode used
    "value": str      # The measured value
}

Low-Level IO

For advanced usage or custom SCPI commands:

write(cmd: str)

Send command to device (no response expected).

mm.write("CONF:VOLT:DC")

query(cmd: str) -> str

Send command and retrieve response.

response = mm.query("MEAS:VOLT:DC?")

REST API

Flask-based HTTP interface for remote access.

Starting the Server

cd multimeter_device
python -m flask --app flask_app run --port 5001

Server runs on http://localhost:5001

API Endpoints

POST /measure

Measure with specified mode.

Request:

{
  "mode": "dc_voltage"
}

Response:

{
  "mode": "dc_voltage",
  "value": "5.00"
}

GET /measure/<mode>

Quick measurement with mode in URL.

Request:

GET /measure/dc_voltage
GET /measure/resistance
GET /measure/ac_current

Response:

{
  "mode": "dc_voltage",
  "value": "5.00"
}

Valid Modes:

• dc_voltage, ac_voltage
• dc_current, ac_current
• resistance, continuity, temperature

Common Patterns

Multi-Measurement Reading

measurements = {
    "dc_voltage": mm.measure_dc_voltage(),
    "dc_current": mm.measure_dc_current(),
    "resistance": mm.measure_resistance(),
}

for name, value in measurements.items():
    print(f"{name}: {value}")

Continuous Monitoring

import time

for i in range(10):
    voltage = mm.measure_dc_voltage()
    print(f"Reading {i+1}: {voltage}V")
    time.sleep(1)

Convert to Float

voltage_str = mm.measure_dc_voltage()
voltage_float = float(voltage_str)
print(f"Type: {type(voltage_float)}, Value: {voltage_float}")

Verify Connection

try:
    voltage = mm.measure_dc_voltage()
    print("Connected!")
except:
    print("Connection failed")

Device-to-Device Coordination

See demo.py for example of using multimeter to verify PSU output:

from psu_device import MP711001
from multimeter_device import MP730027

psu = MP711001("192.168.1.100")
mm = MP730027("192.168.1.99", port=3000)

# Set PSU and verify with multimeter
psu.set_voltage(1, 5.0)
psu.output_on(1)

import time
time.sleep(2)  # Wait for stabilization

measured = mm.measure_dc_voltage()
print(f"Set: 5.0V, Measured: {measured}V")

Error Handling

The driver automatically reconnects on socket errors. No explicit error handling required in most cases.

For custom error handling:

try:
    voltage = mm.measure_dc_voltage()
except ValueError as e:
    print(f"Invalid mode: {e}")
except Exception as e:
    print(f"Measurement error: {e}")
    # Driver will attempt reconnect on next command

Performance Notes

• Timing: 0.15-0.2s delay between commands for stability
• Measurement: Single-shot, blocking. No polling loops.
• Reconnection: ~0.5s delay on error recovery
• Response Format: All measurements return strings (convert with float() as needed)

Specifications

Typical multimeter specifications (refer to device manual for exact values):

• Voltage Range: 0-1000V AC/DC
• Current Range: 0-10A AC/DC
• Resistance Range: 0-100MΩ
• Display Resolution: 3-4 digits typical
• Accuracy: ±0.5-1% typical

Troubleshooting

"Connection refused"

• Check device IP address: ping 192.168.1.99
• Verify device is powered on
• Confirm port 3000 is not blocked by firewall

"Socket timeout"

• Device may be slow; try increasing timeout parameter
• Check network latency
• Ensure probe connections are secure

"Invalid mode" error

• Check mode spelling (use constants or list from docstring)
• Verify mode is supported by device

Measurements reading zero

• Check probe connections
• Verify measurement range for device
• Try a known voltage source to verify device operation

Temperature sensor not working

• Confirm temperature probe is connected
• Some devices require probe to be recognized before use
• Check device manual for probe specifications

See Also

• Main documentation: ../README.md
• Example usage: ../demo.py
• PSU device: ../psu_device/README.md