Compact oscilloscope/recorder provides portable data logging

June 13, 2017 // By Graham Prophet
Yokogawa ScopeCorders are instruments that combine the facilities, as the name suggests, of an oscilloscope and an electronic “chart recorder”. Added to the range, the DL350 is a fully portable variant that is expected to find application making field measurements in wide range of industries.

ScopeCorders are mainframe-plus-plugin format instruments. The DL350 takes two of the range of modules from Yokogawa’s existing suite of measurement front-ends: it is compatible with the complete existing range. The new mainframe has a touch-based interface and has almost no traditional front-panel controls, one exception being a large ‘start/stop’ button to initiate previously set-up measurements. Intended for in-field use the instrument has a built-in battery although this is intended to provide back-up and hold-over power rather than to run the unit stand-alone for long periods. The 8.4-in. touch screen is resistive; Yokogawa comments that its intention was to use a capacitive screen but when evaluating operation in typical industrial environments, it found that capacitive touch operation could not be assured in the presence of high electric fields.

 

The instrument combines features of a general-purpose oscilloscope and those of a high-performance data acquisition recorder. Unlike alternative portable measuring solutions such as oscilloscopes and combined oscilloscope/multimeters, it adds high levels of precision and accuracy to field measurements, isolated inputs for measurements at high voltage levels, and long-memory capabilities that allow long-term recording for many hours or even days. Decode of bus traffic means that a user can directly measure, say, the electrical output of a transducer, and simultaneously view or log what their system’s microcontroller “thinks” it is seeing.

 

Module options can selected from 18 types to carry out high-precision voltage measurements, or handling a blend of signals coming from such inputs as current probes, temperature sensors, strain gauges, accelerometers and serial buses. For example, four isolated 16-bit voltage inputs can be measured at speeds of one megasample per second alongside 16 temperatures or two separate CAN or LIN buses each containing 60 signals. Changing a single module enables measurement at 100 Msample/sec at 12 bits and 1 kV of isolation. The company adds that almost the only change needed to its range of modules has been an update to increase the isolation level on certain variants. 16 logic inputs are always available, with even more available by swapping a further module. AC measurements use an RMS module, and a mathematics channel for signal processing and analysis after the recording is finished is included.

Recorder mode is suitable for long-term, continuous recording for a specific duration and where the sampling interval is specified. A set-up wizard can be used in this mode to guide the operator quickly through the entire set-up process. Scope mode allows the DL350 to be used just like an oscilloscope with all the associated benefits, including comprehensive triggering and flexible memory use. Using the history memory enables up to 1000 separate triggered acquisitions to be captured to the internal memory so that the causes and effects of abnormalities can be carefully analysed. Up to 5 Gpoints of data per module can be recorded directly to an SD card. This means that the DL350 can be used for continuous recording up to 50 days. For high-speed signals, up to 100 Mpoints per module of internal memory is available to capture fast transients. This is up to 10,000 times more than other portable oscilloscopes or oscilloscope/multimeters, the company asserts. Oscilloscope-style features such as complex triggering with waveforms masks is avaialble.

 

A high-resolution, high-speed sampling module provides individually isolated 12-bit, 100 Msample/sec inputs, which can precisely measure and record transient waveforms (superimposed on inverter outputs, for example) and the edges of control signals which cannot be measured by traditional handheld recorders or oscilloscopes. A DL350 can be left unattended with the captured waveform automatically saved to a file, or a notification email sent if and when it triggers.

 

Power, in single and 3-phase systems can be evaluated; for fundamental waveforms of 50 or 60 Hz, up to 40 harmonic orders can be analyzed. Alternatively, it is possible to use the suite of FFT functions to perform full frequency analysis.

 

The DL350 is based on an A4-sized compact chassis and weighs less than 2.6 kg excluding battery and under 4 kg when populated with a battery and two, 4 channel modules. The rechargeable battery provides three hours of continuous operation.

 

Yokogawa; www.yokogawa.com

 

next page; Yokogawa’s example ‘use cases’