Introduction

 

This is my opening blog on the DAQ970A data acquisition unit that I was lucky enough to be selected to road test. This is a general blog, with my intention to introduce the DAQ970A.

 

I didn't really do an unboxing as they don't do an awful lot for me, so this section is a little brief. The unit arrived in two separate parcels. The longer, narrower box contained the DAQM901A multiplexer card with its own calibration certificate, one thermocouple and a screwdriver, three other thermocouples in a separate bag, the mains lead, USB lead, BenchVue software on CD ROM, the calibration certificate for the DAQ970A and some general documentation.

 

{gallery} DAQ970A Contents

Boxed items

DAQ970A Arrival

Boxes opened

Multiplexer Card, Thermocouples and accessories

DAQ box opened

DAQ970A mainframe unit

Calibration certificates

Calib ration documentation

 

The other box contained only the DAQ970A unit and another copy of its calibration certificate. Although the unit appeared to be in the manufacturer's box, it was only protected by the two foam inserts seen in the picture. There was no anti-static back covering the whole of the unit, that I would usually expect to see. I do not know if this is just because the unit has been shipped for the road test. The box looks like it has been opened multiple times.

 

The calibration certificates are a little sparse for my liking. The do not contain any data and are more like a certificate of conformity. The certificate for the unit does have a label that can be peeled off and stuck to the unit to confirm the date of the factory tests.

 

A guidance note is also included that allows the next calibration date for the device to be determined. I would probably struggle to get this past an auditor if the DAQ was being used professionally out on a site, so the likelihood is that I would have to send it away for calibration straight after receiving it, or purchase it with an external calibration if that option was available.

 

 

What is a Data Acquisition System?

 

So, now that the unit has been unboxed, exactly what are we looking at? 'Data Acquisition System' is a very generalised term. Just typing the phrase into a search engine gives a plethora of various different options available. A Data Acquisition System can be thought of as;

 

                         "A system that monitors the physical parameters of a piece of apparatus and converts them to electrical signals for analysis within a computer"

 

The key to the definition, is at the end of statement where the interaction with computer based software is added into the system. Sometimes things get confused as units that collect data are termed as data acquisition, but this is really just data logging. Other definitions bring in an element of control into the system based upon the data obtained, moving the functionality closer to that of industrial programmable logic controllers and distributed control systems.

 

The very first data acquisition system was the IBM 7700 developed back in late 1963. This had 32 inputs and could output the processed data to 16 devices such as screens or printers. A year later, the IBM 7700 was replaced by the IBM1800 that was manufactured in the now familiar 19" style racking cabinets. This system introduced control functionality alongside the data acquisition element and units were known to still be in operation until 2010 at a Canadian Power Plant.

 

IBM 1800 Data Acquisition and Control System - Wikipedia

The IBM 1800 Computer - Still in operation almost 50 years after it was introduced

 

DAS Block Diagram

Source: Wikipedia

 

Wikipedia actually has a very good block diagram depicting the main elements of a Data Acquisition System as seen above. The physical elements are monitored using sensors / transducers that convert the data collected into raw electrical signals. These signals have to be conditioned, to allow them to be converted into a digital format that can be analysed by a computer. An analogue to digital converter is used to carry out this conversion. The software running on a computer can then analyse this data and provide information in multiple formats.

 

The DAQ970A from Keysight fits predominantly onto the Analogue to Digital Conversion block of the diagram. However, it does offer some signal conditioning capability and also some analysis capability from the built in 6.5 digit DMM. Further analysis of data can be carried out utilising the BenchVue software installed onto a computer, as per the more traditional approach of a Data Acquisition System.

 

Market Review

 

The DAQ970A is Keysight's latest data acquisition unit coming into a family of 10 other units and is classified as a desktop style unit, offering similar functionality to their older 34970A and 34972 units. The manufacturer's comparison of the three units can be seen below.

 

Keysight DAQ Family

Source: Keysight

 

However, Keysight are only one manufacturer, with a desktop style Data Acquisition System. Notably, Keithley, Fluke and Rigol are all mainstream instrument manufacturers that offer this style of instrument.

 

DAQ Comparison Table

The above table is only a sample of the information available. I did find it quite hard to produce an accurate comparison as the performance of these units is very much dependent upon their configuration. For the purposes of the comparison, I have stuck to bench top style units with a DMM available, either built in or as a module card.

 

The Rigol comes in as the cheapest unit, but it also offers the least functionality in terms of modules available. One slot is also taken up for the DMM module, the price given is for the M300 frame with the DMM module supplied. All the other units come with the DMM built into the frame. Some of the Keithley and Fluke units have access to the DMM via banana jacks on the front of the meter, which allows them to have a CAT II safety rating and in the case of the Keithley read up to 1000V DC. The multiplexer cards however are limited to 300V.

 

The majority of the units can log to USB as well as internal memory. The number of scans it can store, is very much dependent upon the configuration of the unit. Where this value was not available from the manufacturer, it has been calculated based upon the number of single wired channels.

 

Accuracy and function wise, the units are all fairly similar. The more modern DAQ970A and DAQ6510 units have added capacitance to their functions, however, this remains missing from the Rigol unit. The scanning speed is based upon the fastest card available, which is usually the solid state multiplexer and it can be seen that the units that do not have this type of module available, naturally have a lower scan speed.

 

Software and connectivity options are variable. The more modern units tend to have more options built into them as standard. All of them have a LabView driver available, only one of the older units appeared not to have a built in Web Server. Some of the units come with free basic software from the manufacturer with an upgrade available for more enhanced functionality. Whilst BenchVue does come with free with the Keysight units, the DAQ App also needs to be obtained to make use of it within BenchVue and this adds extra costs. The cost given however, is for a perpetual licence that can be transferred between computers, other more restrictive, but cheaper options are available.

 

Cost of Ownership

 

So what is the real cost of ownership?

 

The minimum requirement is the DAQ unit and then a relay type multiplexer card. For the Keysight DAQ790A, this comes in at £1869.80 for the DAQ unit and a 16 channel multiplexer. In comparison the Keithley DAQ6510 would come in at £1,738.00 for the unit along with a 20 channel multiplexer. The Rigol comes in at £1,615.00 for the mainframe, DMM module , 20 channel multiplexer and a termination module when brought separately. However, a package offer exists from Rigol for all of these items for a total of £1,441.00.

 

Fluke comes in at the highest price, and a functional system of the mainframe, 22 channel card and input board can be purchased for £1940.00. It is also worthy noting that the Fluke acquisition unit, does not offer the other different types of modules available from Keysight and Keithley and to some extent Rigol, and only has a voltage multiplexer available.

 

If calibration of the data acquisition unit is required, then this seems to be available in the UK for around £125.00 for a standard calibration and £150.00 for a traceable UKAS calibration. The final cost would then be the software, which is probably required to make the most out of the unit. Keysight though, appears to be at the more reasonable end of the price scale where the software is concerned. So for a working, calibrated data acquisition system;

 

Prices are UK based, excluding VAT.

Keysight:- £2,208.80

Keithley:- £2,074.00

Fluke:- £2,303.00

Rigol:- £2,198.00

 

For me a Keysight DAQ907A or a Keithley DAQ6510 package would offer the best value for money with better options for future expansion. Whilst the Keithley mainframe is slightly better priced, the modules tend to be priced higher than those from Keysight, so over the longer term, the Keysight would probably become better value. The Rigol unit sees a larger increase due to the price of the software, unless the basic software that comes with the unit will suffice. In comparison to the Keysight and Keithley it does not have the same level of flexibility. The Fluke offers a poor solution in comparison, higher priced and with less options than the Rigol unit, I just don't see how it competes.

 

This is a very light look at the market for these units, there are a lot of USB based instruments that are much more cost effective, but are not standalone like these. At the other end there a remote specialised oscilloscope based data acquisition systems from the likes of Hioki and Graphtec, that would come in at 4 to 5 times the price of the Keysight.

 

Module Types

 

Without a module inserted into the frame the DAQ970A will not do much for you. The Keithley DAQ6510 and Fluke 2638A will operate as a bench multimeter using the front sockets, without modules plugged in, but this isn't utilising the logging or control functionality offered by the modules.

 

To get basic functionality, a multiplexer card is required. These come in three formats, electromechanical relay type, reed relay and solid state. Solid state boards offer the highest scanning speeds and do not suffer from the electrical and mechanical wear associated with the relay type multiplexers. Naturally, they are the most expensive. Some multiplexers offer single wire channels with a common terminal acting as the return, whilst others offer 2 wire channels to give electrical isolation to the parameter being measured. Some of the two wire multiplexers allow the channels to be paired to give 4-wire resistance measurement.

 

Some multiplexer cards offer further functionality with current channels being added, whilst other manufacturers have split voltage and current multiplexers, that usually have a higher voltage and current reading capability.

 

DAQM901A Multiplexer Card

This is the DAQM901A 20 channel multiplexer card that comes as part of the road test. The relay arrangement to the right shows the basic functionality of the card. The channels are divided into two banks of 10. Each bank has a common terminal for both the high and low connections for each channel, allowing the channels to be utilised as single wire with a common return. Alternatively, each channel has its own double pole relay so that it can be used as a 2 wire connection.

 

To enhance the DAQ unit's ability to read temperatures, this multiplexer card also has a built in reference sensor to improve the accuracy of the readings.

 

The internal DMM has its two if its own double pole relays to switch either the source or the sense connections through to the channel being measured. This particular card, also has two current channels each with their own double pole relay and a further double pole relay for the DMM current input. A with the 20 voltage channels, common terminals also exist for for the current channels. Specifically for the current channels, a double pole shunt relay is fitted for each channel. This shorts out the current channel when it is not being measured by the DMM, so the current keeps flowing through the circuit under test.

 

Matrix switch

An adaptation of the voltage multiplexer card is the DAQM904A 4 x 8 two wire matrix switch. This provides a switching matrix to allow the circuit being tested to be connected through to other instruments or functions as required. The electrical layout of a matrix switch is depicted on the left.

 

A matrix switch however does not provide the same isolation as a multiplexer card and it is possible to configure a column to be connected to multiple rows at the same time, or vice versa. The user therefore, has to be aware of the switching configuration and ensure that they do not introduce short circuits or switch voltages onto unwanted terminations by mistake.

 

Multiplexers and matrix switches are generally used for low frequency signals. For higher frequencies, Keysight offer the DAQM905A RF multiplexer that allows test signals up to a 2Ghz bandwidth to be routed through the matrix to other test instrumentation or from signal generators. This is a more specialised card and sells for around 25% more than the general purpose relay multiplexer cards.

 

After the multiplexer and matrix cards, the modules move towards providing control functionality. Keysight have provided two offerings, the DAQM907A multifunction card and the DAQM903A actuator card. The actuator card is simply a 20 channel single pole changeover card, that allows devices operating up to 300V and 1A to be switched on or off by the DAQ unit.

 

 

 

The multifunction card provides 16 digital input / output channels, two 12 volt / 24mA analogue outputs and a 100kHz totaliser. Multifunction card

 

The digital inputs and outputs are TTL compatible and can be used for monitoring systems or controlling TTL compatible circuits. The outputs are controlled directly from the DAQ unit or the software.

 

The totaliser is also TTL compatible and can be driven by limit switches or other types of sensors. The value from the totaliser is read by the DAQ unit only during scanning.

 

The analogue outputs can be configured to source voltage or current and also offer two sense channels for improved control. Its value is easily set within the DAQ unit as seen below.

 

Analogue output

 

Build Quality

 

The instrument is housed in a steel case, with removable rubberised mouldings at each end protecting the plastic end panels. At the rear of the meter, there are the slots for the three modules, IEC mains input connector, LAN Socket, USB socket, a 9 pin D-Type socket for alarms and external trigger connections, an earth terminal screw and a slot for a Kensington lock.

 

At the front, there is the 41/4" colour LCD display, soft keys and rotary knob for control functions and a USB port for saving results to external memory.

 

A 3 position tilt/handle is fixed to the side of the case that can be positioned underneath to allow the instrument to sit flat, at 90 degrees to tilt the instrument upwards, or at 180 degrees to act as a carrying handle. Twisting the handle through 270 degrees to the top allows the sides to be pulled out and the handle removed completely.

 

A 2" square set of 1/8" holes have been pressed into the sides of the case in opposite corners to provide cooling air flow. The fan is located at the rear corner to the side of the mains inlet. There is not any form of filter for the fan.

 

Externally, the unit is immaculate, with no signs of any scratches or dints t the case or plastic mouldings. All the lettering on the covers and buttons is clear an easily readable.

 

Taking the unit apart, initially involves the removal of the carry handle and the two end rubber mouldings. Two screws are undone to release the rear cover, the screws are retained within the cover. A single screw underneath then holds the outer case in place, removal of this, and the case can be slid away backwards to reveal the instrument inside.

 

Inside, the unit was found to be clean, with no signs of debris or residue from soldering. Underneath the main PCB, a CR2032 battery is located to backup the real time clock, measurements stored in the instrument and the module and power on status.

 

The main multimeter is built into its own module that is secured within the frame by a single screw and a plastic latch towards the rear of the module. An IDC lead connects the multimeter module to the main PCB at the rear, and a multiway single in-line plug and socket connect the module at the front. With these unplugged the multimeter module can be removed completely to reveal the main power supply and LAN/USB connectivity circuitry.

 

 

{gallery} DAQ970A Build Quality

Steel outer case

Outer case made of steel

Single securing screw

Single securing screw for outer case

Steel internal chassis

Internal chassis is also steel

Bottom PCB

Bottom of PCB with Battery

DMM Module Removed

Multimeter module removed

Power Supply Module

Power Supply Module

LAN and USB Controller

LAN and USB Controller

Back plane for module sockets

Back Plane for module sockets

Front Panel PCB

Front panel PCB

Front PCB MCU

MSP430 Microcontroller on Front panel PCB

Damaged socket on front PCB

Damaged socket on front PCB

Mating socket

Undamaged receptacle on main PCB

DMM module top side

DMM module top side of PCB

DMM FPGA

DMM module Lattice FPGA

DMM module bottom PCB

DMM module underside of PCB

DMM IoT Chip

DMM module Texas Instruments 32 bit ARM MCU

 

The front panel is removed as a whole unit. One screw secures it at the side and then the plastic moulding is pushed over the bosses on the steel chassis. There is a 'Centronics' style connector that links the front PCB module to the main board. A small sliver of the outer plastic shell was found to be broken off, presumably as the unit was assembled in the factory. Other than this very minor issue, every thing else inside was found to be spotless.

 

The DMM module can be opened up by removing the support pillar that secures it into the case and puling off the lid. As expected from Keysight, everything inside was immaculate, with no signs of damage or manufacturing residue. Unlike the rest of the chassis, the case for the multimeter was in aluminium.

 

On the top side of the PCB there looks to be the relays for switching the DMM module in and out of circuit, being of the elctromechanical type, these will obviously have a life span, but it looks like the multimeter could be replaced as a complete module if issues arose.

 

Power Consumption Tests

 

The instrument does not have a hard power switch and needs to be turned off at a wall socket or unplugged to remove power from it. The on/off button at the front just switches it between standby and operating modes, so I was curious to see what the power consumption was. Looking at the power inlet to the instrument, the voltage range should be between 100V and 240V with a maximum load of 75VA. The specifications within the manual allow for a further 10% on these voltages.

 

DAQ970A Mains inlet

 

The following video is 3min40s long and shows the startup tests for the nominal UK and North American voltages / frequencies.

 

 

The tests were carried out by powering the unit from a BK9801 AC Power Source. The results were quite intriguing. Below is a screenshot of the data capture from the BK9801. This data was captured at the nominal, minimum and maximum voltages for UK domestic mains (230V), UK industrial supply (110V) and North American supply (120V).

 

230V mains test

A plot was made for each supply voltage with its minimum, maximum and nominal traces.

 

{gallery} DAQ970A Power Consumption

120V 60Hz Power Consumption Data

USA Mains Voltage Applied

110V 50Hz Power Consumption Data

UK Industrial Mains Voltage Applied

230V 50Hz Power Consumption Data

UK Domestic Mains Voltage Applied

 

In terms of profile shape, all three supply voltages showed a similar response. The initial inrush spike is seen as the mains is applied to the unit, this then drops down to the standby load being drawn, this is followed quickly be a second smaller inrush, the cause of which has not been determined. The current is then seen to jump up in two distinct stages, the first as the on/off button is pressed and the second as the unit goes through initialisation, finally setting down on its operating load, until it is switched off and returns to the standby load. The second spike isn't seen with the UK domestic supply, but the initial inrush seems to be much larger for both 216V and 230V.

 

DAQ970A Power Consumption Comparison

The power consumption comparison in the table above shows that in standby mode, nearly twice the power is drawn when powered from a domestic UK supply in comparison to the lower UK industrial and North American supplies. With the unit in operation, the power difference does decrease, with the UK domestic supply being around 25% higher draw. Presumably, this difference is down to the efficiency of the power supply, even when operating, the power factor fluctuates between 0.3 and 0.5.

 

Performance Tests

 

Keysight have a service manual freely available for the DAQ. This is quite comprehensive and includes dismantling procedures, performance tests and a full calibration procedure. The performance tests are split into a quick test, limited to 15 different tests across the various meter functions and a full performance test that has 43 DC test points and 37 AC test points.

 

To carry out the tests, the DAQM901 multiplexer card supplied is placed in to slot 3 of the DAQ unit. Short circuit tests are carried out on Channels 03 and 13, for this I just made up a wire short to link the 4 terminals together.

 

Shorting link installed

 

Voltage, frequency and resistance tests are made on Channel 02 and current tests on Channel 21. For the DC voltage and current tests I have a Keithley 2450 SMU, although the output is limited to 200V and cannot make the 300V test. For 300V I can use an injection test set, but the output accuracy of this is much lower than the SMU. For frequency tests, I have a Rigol DG1022 available, cross referenced to a Keysight 53220A. The AC voltage and current tests are a little more challenging. I can cross reference all voltages and currents injected to a Fluke 8846A, 6.5 digit bench multi-meter. I have the current amplifier I built that can inject 0 to 1A up to 100kHz and a voltage amplifier that can inject 0 to 250V up to 500kHz, both utilising the DG1022 to provide the reference signal.

 

DC Voltage Test

 

10V AC Voltage Test

 

AC Current tests

 

Resistances are checked with a Time decade resistance box and some fixed value resistors I have for checking meters. The values of these are also checked with 8846A. I also have a DMMCheck Plus from Malone Electronics that can be used to check a few test points.

 

A 6m video of a few of the test points measured and some amusing operation of the source measurement unit providing the power.

 

 

{gallery} DMMCheck Plus Tests

AC voltage check

5V AC Measurement with DMMCheck Plus

100 Ohm Resistor Measurement

100 Ohm Resistor Measurement with DMMCheck Plus

DMMCheck Plus Test Result

DMMCheck Plus Test Results

Deviation from original cal

Deviation of readings from original calibration data

The tests with the DMMCheck Plus went very well, with the largest deviation from the original calibration readings being a mere 0.018%.

 

The Keysight 53220A and Fluke 8846A are two meters that I keep independently calibrated to UKAS traceable standards on an annual basis, so I am reasonably confident in the results they provide. The 2450 was last calibrated two years ago, and has proven to be a pain to get checked in the UK. As the tests progressed, I did struggle to get correlation between the two meters for some of the readings so I repeated these with a Keithley DMM7510 7.5 digit multimeter and managed to get acceptable readings for all, apart from one AC test voltage of 70V at 300kHz. Overall, 11 readings produced results wider than the tolerances when using the 8846A. This dropped to only the one reading when using the DMM7510.

 

AC Voltage Test

 

Quick performance test results

DC Performance Tests

 

AC Performance Tests

At the end, the unit performs within specification. The one excursion and a few others that are close to the tolerance limits are more likely down to the test equipment I used and the setup. Tolerances to the mV / A and uV / A are usually achievable, but this unit is getting down to nV / A and even pA, which requires specific test methods to minimise noise issues which I am still learning about.

 

Even some of the test instruments seem to conflict with one another. I could not get the 53220A counter to measure frequency in parallel with the DAQ unit. On their own, the frequency readings are accurate and very thing seems fine. The 2450 SMU had some setup issues and the voltage it was set to put out, was actually found to be higher than the setting, this was resolved by setting the SMU to source and measure voltage.

 

 

Operating as a Standalone

 

With a built in DMM, the DAQ970 can be set up and used without connecting it to a computer. For an initial look at the unit, I decided to take this approach and set it up to monitor the temperatures, voltages, frequency, load and gain of the current amplifier I have been experimenting with. This gave the opportunity to compare results to the thermal imaging camera, that I have had doubts about.

 

Another 6m video showing the connection of the multiplexer card and connecting up the current amplifier to be monitored.

 

 

The test set up only utilised the DAQ unit and the Rigol waveform generator to provide the signal to the amplifier. The DAQ unit essentially replaced the use of the oscilloscope, bench mulitmeter and thermal camera. It also gave the opportunity to take multiple readings over a period of time automatically, instead of me standing around and manually writing down readings, or saving them to a computer when required.

 

The maths feature was also used within the DAQ to set up the current clamp ratio, so that the channel would display the current being drawn in Amps instead of mV and me doing the conversion manually. A calculated channel was also set up do decide the output voltage by the input to display the amplifier gain.

 

 

{gallery} Amplifier test with DAQ

multiplexer terminations

Multiplexer module terminations

Wiring jumble

Wiring from multiplexer module

Test set up

DAQ Test setup for amplifier

Thermocouple attachment

Thermocouple attachment to amplifier components

Scan list within DAQ

Scan list within DAQ

Amplifier gain calculation

Computed channel for amplifier gain

Current clamp ratio

Using the math function for the current clamp ratio

Current measurement check

Comparing the current measurement to a DMM

Scan interval setting

Setting the scan interval

Copying data to USB

Copying data to USB

 

For me, it is worth noting that the thermocouples sent with the DAQ conform to the ASTM and not the IEC colour coding that I am more used to.

 

Thermocouple colour codes

Source: ThermocoupleInfo

 

This video is a 12 minutes long and goes through setting up the a channel of each different type and then adding in the math functionality towards the end. I think overall it took me about 20 minutes to setup the channels directly on the DAQ unit.

 

 

For a trial test, I set the DAQ to record a data scan every thirty seconds for ten scans, thinking this would give me five minutes of data. I didn't realise that I would actually need eleven scans for five minutes as the first scan is carried out immediately at the start of the scan. Despite that little discrepancy, the data collection went smoothly, requiring no input from me. You can set up a particular channel to monitor during the scan on the DAQ unit and change this if required, without stopping the data collection sequence.

 

The video of the data collection lasts about 6m30s and you start to see the issue regarding using the current channel for this particular application.

 

 

The following 5m video goes through the observations made of the current channel on the DAQ affecting the operation of the current amplifier.

 

 

Actual analysis on the DAQ unit itself once the data has been collected is not very useful, the data can be viewed as a list or a plot and some basic statistical data can also be viewed. All of these can be saved as screenshot and copied to USB for transfer to a computer.

 

Scan list on DAQ  Statistical data from DAQ

 

Alternatively, data can easily be exported to a USB stick in the form of a CSV file, for transfer to a computer and analysis in Excel. It was found that the DAQ only saves one set of scans, so if a scan is repeated the original data is lost unless it is saved to USB prior to the next scan.

 

Once in Excel, the data can be formatted, analysed and a variety of plots produced. The two pictures below give an idea of what can be achieved. One thing that was noted, is that the channel name created in the DAQ was not saved with the data, only the channel number. Something to remember if you were sending the data of to someone else for analysis.

 

Test run data table

 

Amplifier test plots

 

Operation with the BenchVue software.

 

The DAQ arrives with a CDROM with the BenchVue software to load onto a Windows computer. BenchVue is also available for download from the Keysight website. In hindsight, this would be the better route as the CDROM did not contain the latest version of the software. It took about 45 minutes for the software to load onto my computer from the CDROM. Download of the latest version took just over an hour for me.

 

Whilst the BenchVue software is free to use, it cannot do much on its own without an application package, which Keysight have available for a good range of the instruments. These applications though are licensed in a variety of options from short term to perpetual and single computer to transferrable.

 

In order to set up the DAQ unit in BenchVue, I found that the unit had to be plugged connected to the computer to allow the software to read the module type. There did not appear to be an option to configure a DAQ in the software and then download it to the instrument. This is the scenario I have been used to with other instruments I have used. This isn't really a big issue, it just makes work tasks a little longer on site if you haven't been able to set up the configuration prior to getting to site.

 

Setting up the test for the current amplifier using the software was much faster and efficient than using the DAQ unit on its own. The majority of the configuration elements are on one screen with the use of drop down boxes to select options making configuration so much easier. Math and alarm functions were found to be immediately available for each channel making their entry much more efficient.

 

Once the configuration is completed, a display screen can be set up to monitor the data collected. A basic strip chart can be used, but there are a number of options available, referred to as 'gadgets' within the BenchVue software. The video is 7 minutes long and covers a brief use of the BenchVue DAQ application and setting up the channels for monitoring the current amplifier.

 

 

Approximately 8 minutes of setting uo the scanning in BenchVue, collecting some data and brief overview of the analysis available within BenchVue.

 

 

Selecting the scan rate and interval is achieved in a separate tab again with all the options available in a clear and concise manner. Scanning can then be started and the instrument goes in its merry way happily collecting data and feeding.

 

Whilst connected to the computer, I did find that operating the buttons on the DAQ would temporarily disconnect it from the software, that would then need to be manually confirmed to reconnect and continue with the scanning.

 

Once the scanning is completed, the data can be exported for analysis in MatLab, Excel or a CSV file. Screenshots can also be saved either to the Windows clipboard or as a separate file or automatically sent to a new Word document. The only thing I did find is that the screenshot option was that of the complete current screen as seen below and not just a capture of the graphic display.

 

Histogram example

 

Analysis options within the BenchVue software are a little basic and to get the most out of the data, I did find exporting it out to another package to be the most favourable option. The video below (2m20s) shows how the data is exported to Excel and the differences between exporting the data directly from the DAQ and from BenchVue.

 

 

 

Summary

 

This is a very versatile instrument that can be utilised as either a standalone device or computer driven to enhance the efficiency of the setup and the level of data collected. It provides a number of options to monitor a system and even control it, that would require a multi-instrument setup making time syncing of data more awkward.

 

The instrument is fairly unique on the market, it does have some competitors from within Keysight themselves and probably from Keithley as the most direct competition. Other vendors provide some systems, but they do not have the same level of flexibility offered by the Keysight unit. There are of course, an abundance of USB driven data acquisition units available within the market, but these have to remain connected to a computer to be utilised. The DAQ970A offers the ability to be taken to a bench as a standalone instrument and carryout a monitoring task without being connected to a computer without any loss of flexibility, although efficiency in setting uo the instrument is impacted.

 

The burden on the current channel did cause issues with this particular test setup. It is also exacerbated by the change in the burden from when the current channel is being read to when the instrument is reading the other channels. Had I not been comparing the current to another meter, this would have led me to believe that the circuit was not providing as much current as it actually was. If the test circuit had of been a constant current source then the burden would not have mattered as much.

 

Build quality was stunning and accuracy tests showed the instrument was up to the manufacturer's specifications. The few hiccups that occurred during these tests were often traced down to the basic setup that I use for carrying out performance checks. When carrying out measurements to the level of accuracy offers by this instrument, external noise will easily impact on readings if the rigid test configuration requirements are not implemented and followed.

 

I will now move on to my RoadTest review, where I will aim to show how the instrument performs specifically on the tests that I have devised for it in my application.