Agilent U1273A Multimeter – using the IR-USB Adapter with Linux

Product Information

The Agilent U1273A is a handheld digital multimeter (DMM) with OLED Display. It has the following capabilities and specifications:

  • Voltage Measuring Range DC: 30mV to 1kV
  • Voltage Measuring Range AC: 30mV to 1kV
  • Current Measuring Range DC: 300µA to 10A
  • Current Measuring Range AC: 300µA to 10A
  • Resistance Measuring Range: 30ohm to 300Mohm
  • Frequency Measuring Range: 99.999Hz to 999.99kHz
  • Capacitance Measuring Range: 10nF to 10mF
  • Temperature Measuring Range: -200°C to +1372°C
  • No. of Digits: 4-1/2
  • DMM Response Type: True RMS
  • DMM Functions: AC/DC Current, AC/DC Voltage, Capacitance, Continuity, Diode, Frequency, Resistance, Temperature
  • Ranging: Auto, Manual
  • Display Count: 30000
  • SVHC: No SVHC (20-Jun-2013)
  • Bandwidth: 100kHz
  • Manufacturers Warranty: 3 Years


Handheld Digital Multimeter with an OLED 4.5 Digit Display, Water and Dust Resistant

The U1273A is shaped perfectly to fit in your hand, with or without gloves on. Its nonslip ergonomic shape enables you to carry your DMM and perform measurements on the go easily. Additionally, the controls are easy to operate due to the large knob and buttons.

  • Organic LED (OLED) display for high brightness level and wider viewing angles (up to 160 degrees)
  • Features set that meet traditional industrial requirements and improve productivity and safety
  • Intelligent features to improve productivity and safety
  • Visual and audible continuity indication in noisy environments
  • Easy access to fuse for simplified maintenance
  • Easy connectivity to PC and internal memory (up to 10,000) for data logging
  • Large rotary switch and buttons that are easy to operate
  • Dust and water resistant casing (IP 54 compliant)
  • Compatible with U1177A IR-Bluetooth adapter for remote monitoring & datalogging

Standard test leads, test probes with 4-mm tips, K-type thermocouple and adapter, 4x AAA batteries and Quick Start Guide.

  • Industrial
  • Maintenance & Repair
  • Test & Measurement


  • IR-Bluetooth Adapter
  • IR-USB Adapter

The IR-USB Adapter

The adapter shows up in dmesg as:

usb 6-2: new full-speed USB device number 2 using uhci_hcd
usb 6-2: New USB device found, idVendor=067b, idProduct=2303
usb 6-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 6-2: Product: USB-Serial Controller
usb 6-2: Manufacturer: Prolific Technology Inc.
usbcore: registered new interface driver usbserial
usbcore: registered new interface driver usbserial_generic 
usbserial: USB Serial support registered for generic
usbcore: registered new interface driver pl2303
usbserial: USB Serial support registered for pl2303
pl2303 6-2:1.0: pl2303 converter detected
usb 6-2: pl2303 converter now attached to ttyUSB0

Serial Protocol

The communication with the U1273A works with a simple text based protocol. Open the virtual serial port with the settings 9600, 8, n, 1. The line break is a simple \n newline character.

The serial protocol of the multimeter is very similar to the Agilent U1272A, which is in part described in this forum post. Here is the table of commands found there:

Command Explanation
*IDN? Identification
SYST:BATT? Request batter status. Not sure what units are returned.
CONF? Request configuration (e.g. "VOLT:AC +5.00000000E+00,+1.00000000E-04")
STAT? Request unit status. I have not decoded the meaning of the return value for this. (e.g. "000000I00302L00004001")
FETC? Request current reading (and FETC? @2 returns current reading on secondary display)
*RST Meter reset
SYST:VERS? Unknown, my meter returns 1990.0
SYST:ERR? Unknown, probably returns the last error
READ? Request current reading. I don't believe that the @2 option works for this command. If your meter supports logging (manual or auto) then the following commands can be used:
LOG:AUTO xx Request value of auto-log position xx
LOG:HAND xx Request value of manual log position xx

A more complete description of the protocol is to be found in the file Protocol reference from the dmmutils project.

Example Conversation over the IR-USB-Adapter

Agilent Technologies,U1273A,MY54010074,V01.95
"VOLT:AC +3.00000000E+00,+1.00000000E-04"

created with this Python code:

#!/usr/bin/env python

import serial
import time

ser = serial.Serial('/dev/ttyUSB0', timeout=0.5)

def send_receive(command):
    ser.write(command + '\n')
    received =
    received = received.replace('\n','')
    print received
    return received


Third Party Software



Python Script by drjoe047

Found here: