Virtual Metrix DC Energy Meter is a general purpose, high performance DC power/energy measurement device optimized for embedded applications. The meter is accompanied by a highly capable software (XPerf) which provides integration of captured power data with the target device's system data. Together, VMX XPerf and E-Meter represent a high quality power monitoring toolkit for embedded and Android applications.
|Full dual channel for simultaneous energy/power measurements|
Exceptional DC accuracy and low noise (similar to 6-1/2 digit DMMs)
|140 Ksps raw sampling rate, each channel|
|Up to 30V voltage support for general purpose applications|
|Continous 6A/7A/10A measurement current (depending on model)|
|High dynamic range with two current ranges: 5A, 20A|
|Ultra precision metal foil shunts|
|Low value shunts (50 mOhm) for minimal burden voltage|
|Automatic offset calibration|
|USB and Ethernet connectivity with USB bus powering support|
|Analog probe for external shunt support|
|Digital channels (2x RS485)|
|Windows/Linux compatible software|
|Embedded applications: Android phones, smartwatches, other.|
Full dual-channel with high sampling rate
The meter implements two energy capture channels allowing it to perform two simultaneous energy/power measurements for increased monitoring flexibility. Each energy channel is utilizing completely separate current and voltage sub-channels, which are sampling input data at 140 Ksps and performing current-voltage multiplication in hardware in order to generate power samples at the same rate. The raw samples are subsequently downsampled / averaged internally to a lower output rate as optimally configured from the XPerf application. The output rate can also be maintained at high/maximum values for a full utilization of the 65 KHz bandwidth of the meter's acquisition channels.
Exceptional DC accuracy and low noise
Equipped with high precision 24-bit circuitries for both the analog front-end and A-to-D conversion, the meter possesses excellent DC measurement performance which is similar to 6½ digit DMMs. This allows a high dynamic range with excellent accuracy and ability to measure currents lower than 100 uA on the 5 A measurement range. For the embedded applications such as mobile phones the main benefit of the increased performance is the capability to accurately measure both the very low currents of standby states and the high current peaks of normal operation mode without the need of changing the measurement range. While also supporting the increasingly high currents of the newest multicore handheld devices.
Ultra-precision, low value metal foil shunts
The current channels are utilizing large volume, ultra precision metal foil shunts with excellent loadlife stability and a TCR of max. 5 ppm/oC (-70X/-100X models). This allows the meter to exceed the gain accuracy of regular DMMs for the current measurements. Remarkably, this performance is achieved using a low shunt value of only 50 mOhms, which minimizes the overall burden voltage and optimizes the meter for low voltage applications.
Extended voltage support for general purpose applications.
High voltage applications of up-to 30V DC are also supported, which makes the meter suitable not only for embedded applications but also for other common applications such as those running at 12V and 24V. The E-Meter is generally suitable for all applications where the voltage is variable and cannot be controlled, therefore requiring both voltage and current to be observed.
Two current ranges
In addition to the base 5A current range the meter provides an additional 20A range allowing for monitoring and capture of the high current peaks that may be present for higher current applications. During capture the meter promptly signals all clipping events for any sample exceeding the sub-channel's overrange levels. Continuous current support ranges from 6A to 10A depending on model.
Automatic offset calibration
The meter's front-end amplifiers are characterized by very low offset drift, however the analog performance is also augmented by employing a periodic automatic offset calibration function which minimizes the offset while keeping the unit always ready for capture.
USB and Ethernet connectivity with USB bus powering support
The meter supports both USB and Ethernet PC connectivity and for normal operation it can be powered through USB. When using Ethernet connection or when draining additional power through the probe or digital channel interfaces the meter will need to be powered from an external 5V PSU.
Analog probes support
Additional probe connectors are provided for each channel supporting the capability of using external shunts, for the interconnection of energy probes or just modification of the supported current ranges. The probe connectors provide general purpose high impedance differential inputs for both current and voltage, which can be utilized to accommodate a broad range of probes. An I2C channel is also provided for each connection.
Digital channles & GPIOs
The rear panel includes two digital channels implemented as RS485 interconnection ports for supporting future digital probes and/or expansion modules.
The separate GPIO connector provides four general purpose I/Os implementing sample triggering and filtering functions with multiple I/O standards support.
Windows/Linux compatible software
The emeter is supported through the VMX XPerf software which can operate under both Windows and Linux operating systems.
The picture below depicts the typical usage with the meter connected to a mobile phone and a power supply:
Front/back panel images:
|1||Energy Channels 1 and 2 Terminal Blocks|
|2||Energy Channel 1 Circular Connector|
|3||Energy Channels 1 and 2 Probe Connectors|
|4||General Purpose I/O (GPIO) Connector|
|5||Energy Channels 1 and 2 LEDs|
|7||Digital Channels Connector|
|10||DC 5V Power Jack|
1. Single or dual channel power measurements with application monitoring for Android Phones
The primary usage of the meter is to have one or two phones/embedded devices interconnected through the energy channels. The captured power/energy data will be correlated by XPerf with the target's (Android device) system data, this way making available a complete system overview that is correlated with power information.
Below are the connectivity schemes for single and dual channel setups with 2 Android phones.
XPerf application window for single and dual channel power measurements.
Dual channel power measurements.
XPerf measurements window displaying the idle/frequency residency information, temperature, emeter power information and application load for a test application.
XPerf measurements window displaying the work/idle information, system load, emeter power information and application load for a test application.
2. Power measurements for all types of embedded devices
Below are several power measurements setup using single channel and different types of embedded devices like SOCs, gadgets, router, dual phone setup.
3. Auxiliary channels connectivity
Please consult the product documentation for each specific use case.