Systems and machines in building and factory automation are controlled via bus systems. They have radio, web and/or LAN interfaces as well as state-of-the-art electronic components. If a fault occurs, there are many different causes: inadequate network quality, poor contacting or insufficiently shielded frequency converters. Strong electromagnetic fields from a production machine can also influence control signals and lead to malfunctions. This is why engineers need a measuring device for commissioning, maintenance or troubleshooting of automation components that allows them to safely measure mains voltage and simultaneously analyze sensitive control signals in electronic circuits.

For these purposes, Rohde & Schwarz has developed the R&S Scope Rider, a particularly robust and versatile handheld oscilloscope. It has numerous automatic measurement functions and can integrate up to eight measuring instruments in one: from the digital multimeter to the data logger for long-term monitoring to the logic analyzer that decodes and analyzes serial bus signals. For example, the oscilloscope displays supply voltage and serial control signals in parallel with time correlation. Even an analysis function for harmonics to assess the power quality is possible.

Measure network quality up to CAT-IV environments

The concept of isolated input channels prevents short circuits if the earth and signal connections to two oscilloscope inputs are accidentally swapped. This means that measurements on power electronics can be carried out safely.

© Rohde & Schwarz

If voltages that are dangerous to touch need to be measured, the user requires a measuring device with a corresponding IEC 61010-1 measurement category. In a CAT-IV environment - before the main fuse of a house mains connection - overvoltages of up to 8000 V can occur with a maximum measuring voltage of 600 V. The safety of the user is only guaranteed if the measuring device has been developed and certified for these overvoltages. The Scope Rider, for example, is certified for voltage measurements up to 600 V in CAT IV and 1000 V in CAT III environments. It therefore enables the power quality to be monitored at all points in the electrical installation.

The galvanic isolation of the input channels from each other is also crucial. With a conventional oscilloscope, accidentally swapping the earth and signal connections can lead to a short circuit with potentially disastrous consequences. The fully isolated input channels of the R&S instrument prevent this and at the same time enable differential measurement. Expensive differential probes are no longer necessary and maximum safety is guaranteed for measurements on power electronics.
A common problem in electrical installations are contacts with inadequate connections, which lead to sporadic interruptions in the power supplies. These can be triggered by mechanical vibrations and can be so short that they are not noticeable with normal electrical consumers, but can disrupt the function of sensitive electronic devices.

A wide range of trigger functions make it possible to specifically detect and analyze such causes of faults. For example, short interruptions in the power supply can be detected easily and effectively with the pulse width trigger.

Measurements on drives and power electronics

Drives and power electronics often place a load on the supply voltage in production. This means that the supply network is utilized differently depending on the time of day and machine running times. In order to record the network utilization, the oscilloscope calculates the active, apparent and reactive power as well as the power factor from the measured current and voltage curve. The oscilloscope's integrated data logger also makes it possible to automatically record the configured measurements for up to 23 days simply by switching to logger mode, thus allowing long-term trends to be analyzed.

In addition, the voltage signal behind a drive or frequency converter is no longer sinusoidal but contains harmonics. The European standard EN 50160 specifies the limits within which the voltage signal may fluctuate so as not to cause malfunctions. This can also be quickly checked with the handheld oscilloscope and the 'harmonic analysis function'. This allows the user to analyze harmonics up to the 64th order on up to four channels in parallel. The device measures the level, phase and frequency for each detected harmonic and determines the effective value, distortion factor (THDr) and total harmonic distortion (THDf). In this way, problematic phase shifts, which can lead to significant neutral conductor currents, can also be easily detected. The oscilloscope displays the currently measured levels of all connected channels and - with a slightly darkened background - the respective maximum value of the measurement. The device displays the EN 50160 limit values for all levels as blue lines. If a limit value violation occurs, the device displays an error message. The analysis is designed for base frequencies of 50, 60 and 400 Hz, but can also be configured for an individual base frequency of up to 1 kHz.

Analysis of serial protocols

When analyzing serial protocols - for example to check the communication between individual electronic modules - the trigger & decode functions help. These enable both an analysis of digital communication and the targeted triggering of specific data packets. Various software options for I²C, SPI, UART and CAN/LIN are available for this purpose, which the user can activate via keycode. This allows the user to check, for example, whether sent UART or CAN/LIN control commands are correctly received and processed by a control unit under investigation. He can load symbolic labels into the device and use them to select the required control commands via plain text labels. This makes working with the device particularly easy.

Focus on simple operation

In day-to-day service and maintenance, it is crucial to identify and solve the causes of problems quickly. Every additional hour of work costs money and can result in high follow-up costs due to the downtime of the systems to be serviced. Devices for service and maintenance work must therefore be particularly easy to operate, and lengthy training phases are not possible.

For this reason, particular attention was paid to the operating concept when developing the handheld. With a touch display, operation is as simple as with a smartphone. Deep menu levels have been avoided and the settings for the most important device functions can be accessed directly via the keypad. The particularly generous button layout also allows operation with work gloves.

For particularly awkward or dangerous measuring tasks, the oscilloscope can also be remote-controlled directly from the web browser of a tablet PC or notebook via the integrated WLAN module. The oscilloscope can thus be operated conveniently and safely from a distance.

Eight devices in one handheld oscilloscope

Automatic measurement functions calculate apparent, active and reactive power as well as the power factor from the measured voltage (channel 1) and current (channel 2).

© Rohde & Schwarz

Fault diagnosis in the field often requires very different measurement functions. For this reason, in addition to the oscilloscope function, the user can integrate seven other measuring instruments into a Scope Rider as required:

• a logic analyzer with eight digital channels,
• a protocol analyzer with trigger and decoding function for troubleshooting in serial protocols,
• a data logger for long-term monitoring,
• a digital voltmeter in the 4-channel version or a digital multimeter in the 2-channel device,
• a harmonic analyzer,
• a spectrum analyzer and
• a high-precision frequency counter.

The user can switch between the various device and other operating modes using the blue mode button. The device automatically adopts the setups when switching between functions. For example, automatic measurement functions can be activated in oscilloscope mode and when switching to data logger mode, this takes over the preset measurements and starts data acquisition.

Due to the variety of functions and its performance - it measures up to 50,000 waveforms per second and has a 10-bit A/D converter - the portable oscilloscope is also suitable for laboratory use.

Adapted to the respective measurement requirements

Users can operate the Scope Rider from R&S in potentially hazardous environments via WLAN directly from the web browser.

© Rohde & Schwarz

The Scope Rider is available both as a 2-channel and 4-channel device, in five bandwidth variants from 60 to 500 MHz. All devices can also be configured as mixed-signal oscilloscopes with additional digital inputs. The user can simply activate additional options using a key code. This means that every user receives a measuring device tailored to their needs: a laboratory measuring device with an intuitive operating concept, designed for use in harsh environments.

The Scope Rider therefore offers more than other handhelds on the market, but costs no more than standard handheld oscilloscopes with isolated inputs.

Author:
Dr. Markus Herdin is Product Manager for Oscilloscopes at Rohde & Schwarz in Munich.