Test and record field bus, motors, and power with one instrument


The latest addition to the ScopeMeter series from Fluke has advanced features for installing and troubleshooting field buses and electrical machines. The new ScopeMeter 125 performs a bus health test on industrial buses, for example, which are rapidly becoming a headache for service, maintenance, and installation engineers. The test quickly determines whether the bus is working, and if not, helps to identify the cause. The 125 works with many industrial networks including AS-I bus, CAN-bus, Profibus, Foundation Fieldbus and Ethernet.

In addition, the instrument can test power input, sensor timing, motor windings, drive output timing and power measurements, eliminating the need for expensive, more specialized test equipment.

Like the other tools in the 120 Series, the 125 integrates an oscilloscope, True RMS digital multimeter and dual-input 'paperless' recorder in one instrument, and it's 600 V CAT III safety certified for machinery, instrumentation, control, and power systems. It carries out effective (Vpwm) voltage measurements of motor drive output and has 0.01 ohm resolution on the 50 Ohms range for testing motor windings. User-named data setups make it easy to use.

Simple good/bad readout for Field Bus parameters

The bus health tests of the ScopeMeter 125 find defects like bad or missing terminators, bad cable splits, missing links, incorrect line loading, line interrupts, short circuit conditions and reflections.

The instrument continuously acquires the bus signal and compares parameters to official specifications. It displays bus speed and measures signal quality with 'good' or 'bad' indications for parameters like rise- and fall-time, amplitude, bias level, pulse width and distortion. The instrument checks at the hardware (not protocol) level. An eye-pattern mode allows for a visual check of signal integrity.

Harmonic analysis and power consumption

Extended harmonics analysis of mains waveforms reaches up to the 33rd harmonic. That includes the important 3rd and 5th harmonics, which may be the cause of overheating in neutral wire or motor, as well as flat-topping of the mains voltage from non-linear loads like SMPS units. The wide frequency range covers railway (16.66 Hz) and airplane systems (400 Hz) applications.

Power measurements cover single-phase and balanced-3-phase, 3-wire systems (Watt, VA, VAR and Power Factor). Unlike power quality analyzers, the instrument is not restricted to 50/60 Hz, and can measure power at the output of motor drives and frequency converters.

The Vpwm measurement capability shows the output voltage of motor drives exactly as the motor perceives it. For electrical and combustion engines, the 125 can indicate revolutions-per-minute (rpm), and can be set up for 1 or 2 rotations per pulse, or 1 rotation per 2 or 4 pulses. A 50-ohm resistance range provides 0.01-ohm resolution for checking motor windings and other wiring.

Automating measurements from industrial systems

The Fluke ScopeMeter 120 Series performs automated, stable, and repeatable measurements on motor, switch and similar signals. The 123 has a 20 MHz bandwidth, while the 124 and 125 are 40 MHz bandwidth. All use Connect-and-View to recognize signal patterns and automatically set up correct triggering - especially convenient for quickly measuring multiple test-points.


The Fluke 125/S model adds FlukeView software, for:

  • Documenting - transfer waveforms, screens and measurement data from the ScopeMeter to a PC. Print or import the data into your report.
  • Adding user text to individual ScopeMeter settings - providing guidance to the operator when recalling a set-up.
  • Archiving - create a library of waveforms with your comments for reference and comparison. Store complete Replay cycles for analysis of waveform changes. Store complete memory content of the ScopeMeter on your PC for back-up purposes.
  • Waveform Compare - store reference waveforms, add operator instructions, and send both to the ScopeMeter for waveform comparison and "Pass/Fail" testing.
  • Analysis - use cursors, perform spectrum analysis or export data to other analysis programs.