Identifying input range in PCI-6034E

[ginos]

Hallo I have a couple of questions. I am using K thermocouples to measure temperature using the following Data Acquisition system:

• Chassis SCXI-1000
• Connector block SCXI-1102B
• Terminal block SCXI-1303
• Controller PCI-6034E

Between SCXI-1102B and PCI-6034E which of this two determines the polarity and the gain of the signal?

Does PCI-6034E offer only bipolar mode? (-10V +10V / -5V +5V / -0,5V +0,5V / -0,05V +0,05V)

What are the gain options in the PCI-6034E (although it is software programmable)?

Thank you

[BROhan]

Hi ginos,

You can configure the gain on the 1102B in software. 

As the article mentions, you will want to take advantage of the full input range of your 6034E. You can also select this input range, which will be the -10V +10V / -5V +5V / -0,5V +0,5V / -0,05V +0,05V you mentioned. This input range is configurable through a channel property node or through the Create Virtual Channel VI. I do not believe there is a selectable gain for the 6034E. You can consult either manual for further details:

PCI-6034E

SCXI-1102B

[ginos]

The SCXI-1102B manual in chapter 3-1 mentions that:

"Gain/input range is a software-configurable setting that allows you to

choose the appropriate amplification to fully utilize the range of the

E/M Series DAQ device"

And then continues to mention that there are two ways to configure the gain/range of the analog input:

1. "NI-DAQ chooses and sets the gain for you determined by the input range."

2. "Otherwise, you should determine the appropriate gain using the input signal voltage range and the full-scale limits of the SCXI-1102/B/C output."

The choices in gain is 1 and 100.

As for PCI-6034E I cannot find from the manual which are the possiple gains, although they are set automatically based on the chosen voltage input range.

In conclusion, I would like to add that my effort is to calculate the code width (Code Width=FS/(Gain*2^N) where N=16 for PCI-6034E), which is the minimum detectable voltage change.

[ginos]

After some more reading, I think that I have clarified some things in my mind. Please correct me if I am wrong.

SCXI-1102B has 2 possible input signal ranges: ±10V (gain=1) and ±0,1V (gain=100)

PCI-6034E has 4 possible input signal ranges: ±10V (equals gain=1), ±5V (equals gain=2), ±0,5V (equals gain=20) and ±0,05V (equals gain=200).

Now, I use K thermocouples and I want to measure temperatures between 30℃ and 60℃. According to ITS-90 Table for type K thermocouple 0,039mV corresponds to 1℃ and the above temperature range corresponds to 1,203 – 2,436mV voltage range.

The signal passes from the thermocouples to the SCXI-1102B. The SCXI-1102B must use the range ±0,1V (gain=100). Through connector the amplified signal passes to the DAQ board (PCI-6034E). The board has a resolution 2¹⁶.

The quantization step size must be 0,2V/2¹⁶=3,05μV according to the input signal range of the SCXI-1102B.

So, I assume a scale of voltage from -100mV to 100mV divided into 2¹⁶=65536 steps with a step size 3,05μV. The problem is that I utilize a very small piece of the range of the DAQ board with the temperature range that I want to measure, because the half of the range (from -100mV to 0mV) refers to negative (or zero) degrees of Celsius due to the unipolar mode of the board.

My questions are the following:

Is the board going to re-amplify the signal or not, and if yes which input signal range will it use?

Does the PCI-6034E support bipolar mode also? (According to the manual no. Do you have another opinion?)

Best regards

Giorgos

[Broken_Arrow]

Are you using LabVIEW? If so, I think you are doing this the hard way. When you create a task, your can set it to Analog > Temperature > Thermocouple, then set it to K. Set your min and max to 30 and 60, and you are done, the Analog Read will give you the value in temperature. No gain to set.

[ginos]

Yes I am using Labview and yes I set the temperature limits as you mentioned. But I would like to know how the gain of the DAQ system works. I am writing a project for my university and I have to include the parameters of the measurements, such as the gain, the polarity. the quantization step.

As a matter of fact I have to make an estimation of the total uncertainty of the measurement. Consequently, these parameters are essential.

So I please for your help!

Thank you very much,

Giorgos

[ginos]

Please any idea? I feel a bit lost.

Thank you

Giorgos

[BROhan]

Hi Giorgos,

The parameters you mention (gain, polarity, quantization) are all listed in the user manual and specifications for the E-series devices. Take a look at page 38. All of the device specifications are listed in their manuals.

[BROhan]

Also, the 6034E supports an input range from -10 to 10 V, so it is bipolar.

[ginos]

Thank you very much Rohan for your help. Still I have some unanswered questions.

The SCXI-1102B and PCI-6034E have the following capabilities from what I found in the manuals you told me:

SCXI-1102B
Voltage Range	Gain
-10V to +10V	1
-100mV to +100mV	100
PCI-6034E
Voltage Range	Gain	Resolution
-10V to +10V	0,5	305 mV
–5V to +5V	1	153 mV
-500mV to +500mV	10	15,3 mV
-50mV to +50mV	100	1,53 mV

Now I want to measure a temperature signal from 30℃ and 60℃ (1,203 – 2,436mV) with 5 thermocouples and I want to have the smallest quantization step.

If I just configure 5 channels to measure the above temperature range under the device PCI-6034E in the NI-DAQmx I believe that the signal will have a gain of 100 with a resolution 1,53mV. With this setting I do not take advantage of the gain of SCXI-1102B.

Is it possible to take advantage of both gains and have a better resolution? If yes how are these gains combained? What would be the resolution?

I really appreciate your help Rohan

Giorgos