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Questions tagged [data-acquisition]

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12
votes
3answers
2k views

What is the “Nyquist” rate for sampling the derivative of a signal?

Background: I'm sampling the current through a capacitor. The signal of interest is the voltage across the capacitor. I will digitally integrate the current measurement to obtain the voltage. ...
7
votes
3answers
431 views

Is star grounding sources necessary for this data acquisition system?

Several single ended output and PSU powered transducers are tens of meters apart from each other outputting 0 to 10V DC like voltages. Some are temperature transducers some are force transducers ect....
6
votes
5answers
738 views

How is binary data 'split'?

If one computer sends data, for example 001101, how does the other computer know, where one bit starts and the other one ends? If you were just to monitor the change, you would get 0101, which is ...
5
votes
5answers
474 views

Processing ADC conversion result: DMA vs Processor Registers

I have a periodic ADC conversion (every 50 micro-seconds) and I use the result to do some further calculations and update the PWM load registers. The ADC is triggered by the up-down counter of ...
4
votes
1answer
83 views

Re-wiring experimental apparatus: Questions regarding proper ground, DC power supplies, and precision instrumentation

The apparatus consists of a large metal spherical chamber attached to a metal table. There are two electrical enclosures bolted to the table legs. The chamber is outfitted with multiple servomotors, ...
3
votes
2answers
690 views

Confusion with different recommendations about wiring floating single-ended output sources to differential inputs

I'm trying to configure single-ended floating sources to differential inputs of this data acquisition board which of course uses an instrumentation amplifier and have differential inputs. So I had to ...
2
votes
1answer
85 views

Wrong voltage measured with a DAQ in presence of a RC filter

I'm using a DAQ from National Instruments. Testing my LabView software I noticed that when I plug a 1.5V DC battery in the analog input channels if I connect an RC filter (R=56 kΩ, C=10 uF) to the ...
2
votes
3answers
981 views

4 Wire Strain Gauge to 2 Wire Conversion/Connection

I have the WK-06-12BT-350 ohm WK125BT Strain gauge from Vishay the Gauge comes equipped with 4 wires ( High endurance lead wires). The following document describes a similar gauge: Strain Gauge is it ...
2
votes
1answer
61 views

Order of write and read in Microprocessor interfaced with ADC

An ADC is interfaced with a microprocessor as shown in the figure. All signals have been indicated with typical notations. Acquisition of one new sample of the analog input signal by the ...
1
vote
5answers
553 views

“Multiplexing” thermocouples to an IO board

I'm trying to solve a problem on a project for one of my customer, 'cause we are having hard times to find an appropriate solution. He needs something really simple (more on this later) and as we are ...
1
vote
1answer
59 views

Tape archival data acquisition

I have some old tapes (the compact cassette variant) and an old Technics deck. I want to digitally archive these tapes as best as I can. The original deck is from the late 80s and contains a standard ...
1
vote
6answers
92 views

What is the need for amplifier stage in a data acquisition hardware?

Below is a typical data-acquisition block diagram: As you see above after the multiplexer there is an instrumentation amplifier IA. This IA stage can be shown in more detail as below: Since this is ...
1
vote
1answer
2k views

i2c data rate calculation

I want to estimate the throughput of i2c lines and this is the calculation I have done: Hardware architecture: MCU <---> i2c mux TCA9548A <---> 8 i2c based IMU sensors MPU6050 What am I ...
1
vote
2answers
81 views

where to insert a thermocouple simulator in a circuit?

I have a thermocouple that's connected through several runs of thermocouple wire into a USB adapter and into a laptop where it gets logged. I'm seeing some error in my readings and would like to use ...
1
vote
0answers
34 views

Reliable methods to read data off a flash chip?

I'm trying to read data off of flash chips on a variety of embedded devices I have, and I'm currently using an FTDI FT2232H and flashrom (with soic-8 clips and probes) to extract the data as they are ...
1
vote
0answers
70 views

How can I estimate the minimum baudrate for a given bitrate?

My circuit performs data acquisition at 250 samples/s, 24 bits/sample and transmit this information to the local host (PC) through a bluetooth module that implements the UART protocol. As far as I ...
1
vote
0answers
88 views

ADXL343 data read

I am using a ADXL343 accelerometer in one of my designs and I am getting strange readings from the device. Just to be sure, I would like to confirm that I am formatting the data properly. (I get the ...
1
vote
1answer
99 views

Noise due to stray voltages in a data acquisition system

A single ended earth grounded data-acq. board on the left in the below illustration has inputs coupled by BNC cables coming from force transducer amplifiers A1, A2, A3, A4 as shown on the right: If ...
1
vote
0answers
52 views

Question about noise effects of parasitic common-mode coupling in a single ended system

This question is related to a previous question. Now I'm trying to understand a bit deeper about the phenomenon I will present. (to see bigger view please left click) To make it clear enough I used ...
1
vote
1answer
127 views

How to interpret this CAN bus data and find an equation?

I am trying to reverse engineer the data sent from an old CAN bus data logger. It sends a single ID which is selectable from a dip switch. The only bit of data I am struggling with is the RPM I plan ...
1
vote
1answer
121 views

Oscilloscope stop getting data

I have a Rigol DS1000Z, and I'm using it to sort of log data. I have a wavelength tunable laser that creates an electrical pulse (start of pulse is start of sweep, end of pulse is end of sweep), and ...
0
votes
2answers
140 views

Is this definitely common-mode interference and how can I model and filter it?

A test device which can output voltage between 0 to 10V by a knob is powered by a DC adapter which converts 220V rms(meaning 311V amplitude) 50Hz AC to DC. Device is not a commercial and its adapter ...
0
votes
3answers
157 views

Is there a need for buffering in this case?

.. will be updated soon (in construction with a more accurate information) If the ADC (or the data.acq device) have 100 kohm input impedance, how much accuracy would I lose? Do I need to buffer this ...
0
votes
1answer
220 views

How can I transmit a TTL signal to a computer?

I am designing a data acquisition system including a sensor that outputs a TTL pulse signal (3 wires: power supply, common, and signal). I am trying to determine how to send this signal to a program ...
0
votes
1answer
90 views

A question about differential ended settings for single ended inputs

Reading this documentation, what could be the reason to use 10k if one uses differential ended input settings for signal sources?: I dont know why they recommend 10k but I had 6 channels going to ...
0
votes
1answer
69 views

How to conclude the necessity for unbalanced to balanced signal conversion for this scenario?

This is a bit specific system related question about simultaneous data-acquisition for several transducers. Therefore hope you don’t mind for the long intro and the question. It would be too implicit ...
0
votes
1answer
439 views

RS485 to RS232 conversion?

I need to connect a sensor that uses a RS485 transmission to RS232 or something I can read through the com ports on my data logger. I can't use usb ports or virtual com ports due to the program I am ...
0
votes
1answer
46 views

Scaling up NTC measurement through Multi-Channel Ohm meter

For a test bed, we want to measure temperatures with NTC sensors (~10kOhm at RT) for the range 10°C to 70°C. Our test machine accepts auxiliary signal through CAN-bus, so we used a Raspberry with a "...
0
votes
1answer
42 views

Wiring an on-off switch to the inputs of a daq

I have the following reed switch sensor: I need to connect this switch to counter input of this daq hardware. The only info is the following: How should I connect this to the counter-input? Any ...
0
votes
1answer
49 views

Data acquisition microcontroller approach

I'm prototyping a data acquisition device which interfaces with 64 discrete inputs; 32 analogue and 32 digital (user-configurable as either ON/OFF measurement or frequency/duty measurement). I'm ...
0
votes
1answer
234 views

Why are high-sampling-rate data acquisition boards so expensive? [closed]

An example would be the NI USB-6366. My guess is that it's primarily due to the analog-to-digital converter (ADC) since it should be the component responsible for the high rate conversion, even ...
0
votes
2answers
95 views

Displaying data in engineering units on desktop [closed]

Suppose I have 100 numbers of DSPs whose ADCs are converting analog data into digitals ones. The data may be current,voltage, frequency etc. Now DSP deals with counts only it does not understand ...
0
votes
0answers
40 views

Should I daisy chain start connect or wire separately?

This is related to field wiring schemes and interference. Sometimes tens of transducers are needed to be coupled to a single-ended data acquisition board's analog input channels where the transducers ...
0
votes
1answer
45 views

Is there a problem connecting PSU grounds to earth for an isolated signal chain in this scenario?

For a precision and simultaneous analog signal data acquisition; several force, temperature and acceleration transducer outputs are coupled to a daq board input channels through signal conditioning ...
0
votes
1answer
39 views

Holding signal true for x seconds in LabView

I'm trying to create an automatic startup override system whereby when an ESD override button is clicked, a signal will be held true for 10 seconds overriding my ESD interlocks. This seems like there ...
0
votes
1answer
53 views

How does isolation prevent input signals to float/saturate for differential ended inputs?

A differential ended input data-acquisition board has the following architecture: Here more information. Through screw terminals it takes the voltage inputs and each input first goes to a signal-...
0
votes
1answer
28 views

Investigating the cause of the drift for this system

A force-torque transducer data acquisition system is shown below: As shown in the above illustration, basically a six-axis transducer is powered and amplified by an interface electronics and then the ...
0
votes
1answer
51 views

Experimenting interference effects for different measurement systems

This is about for low level signals interference/noise being observed with single ended data acquisition inputs but not with diff inputs. Basically there are three data acquisition boards, where one ...
0
votes
1answer
73 views

Confusion with grounding floating sources to be used with a differential ended data acquisition board

Regarding this paper, I first tried to wire single-ended floating sources to a diff ended data acquisition board. But because of some power supply related issues and not wanting to make another ...
0
votes
1answer
79 views

How to explain this solution to the common-mode voltages?

One of my previous question revealed that a variable voltage test device's power supply which is an AC/DC adapter, and is SMPS type which causes common-mode voltages. A solution given by tying the ...
0
votes
1answer
119 views

Using differential and single-ended inputs simultaneously in a data acquisition system

Below is the wiring setup I plan to use: Basically the black rectangle in the middle is this data-acquisition board which has 16 diff ended inputs. The blue rectangle on the left is a six-axis ...
0
votes
1answer
189 views

is it possible to design a SD 3.0 controller in UHS-ii/uhs-i mode using simplified specifications?

I've been for while looking to store a sampled data up to the rate of 30MBytes/s, an SD 3.0 host controller core in uhs-ii/uhs-i mode fits the requirements. i'm not planning to buy SD full spec and ...
0
votes
0answers
44 views

Question about earth grounds for remote control of VFD via a DAQ system

A single-ended earth grounded PCI data acquisition board's analog inputs and outputs are controlled by a PC. The daq board has also analog outputs. One of the analog output is controlling the motor ...
0
votes
1answer
31 views

Reverse Polarity Protection for DAQ box

Firstly, I am a ME seeking advice from EE's. I have a Quadvolt voltage data acquisition box from Omega (P/N: OM-CP-QUADVOLT-30V) http://www.omega.com/pptst/OM-CP-QUADVOLT.html, that I intend on using ...
0
votes
1answer
62 views

Worried about channel ghosting in DAQ system - Need unit gain buffer?

I am working on a redesign of a test box we have at work. There is a transmitter that is sending data to a recording system (in my case the dewetron trendcorder with Trion BNC modules). We previously ...
0
votes
1answer
67 views

Are there any benefits to amplify the signal for this case?

A force transducer together with its amplifier designed for a full scale load such that it has -5V to +5V range as output. But it is only used with loads outputting -200mV to +200mV. A data ...
0
votes
2answers
35 views

Comparing two imbalanced signal transmission

Below shows a perfectly balanced system assuming cables are balanced and twisted: Im wondering if the transmitter is not impedance balanced, would a balanced receiver reject CM interference still ...