ADVANCED SPAN AND ZERO ADJUSTMENTS:
The instructions for calculating the resistance value (to shift the
zero) are below:
In this example is 2.5 V corresponds to the Low CSG110 output.
5)
Now we must offset the zero. First we need to calculate the GAIN,
the equation to do this is below.
Gain = (CSG110 Span x 1000) / (Rated Output x Excitation)
Where:
The
CSG110
Span is calculated in Step 3
Often when using a signal conditioner it is necessary to offset the
The
Rated Output
is determined in Step 1
standard 0-10 VDC (or mA values) span. The CSG110 makes this
The
Excitation
is determined in Step 4
simple. The user just needs to determine the correct excitation voltage
and input range to create their desired span and then connect a
Example:
Gain = (2.5 x 1000) / (2 x 5) = 250
resistor in the ISI location shown on the board to off set their zero.
6)
Now that we know our Gain we can calculate how many mV are
CALCULATING THE CORRECT INPUT JUMPER, EXCITATION
required to shift the zero the desired amount. The equation for
SETTING & RESISTOR VALUE
this is below
Determining Input value and Excitation settings:
Zero Offset = Zero Shift / Gain
1)
It is first necessary to find out your sensor ‘Rated Output’ in mV/V
Where:
(listed on sensor certificate).
Zero Shift
is the amount of volts that the zero output from the CSG110
needs to be shifted
Example: 2mV/V
Gain
is calculated in (Step 5)
2)
Determine your desired output from the CSG110. 0-10 VDC is
Example:
the standard output.
2.5 / 250 = 0.010 V or 10mV = Zero Offset
Example: I would like the 0-2mV/V sensor range to correspond to 2.5 VDC – 5
7)
Now that all of the necessary values are calculated you can use
VDC output from the CSG110.
the equation below to calculate the resistance necessary to shift
3)
Determine your desired CSG110 output span. This would be your
the zero.
Maximum
CSG110 Output minus your
Minimum
CSG110
Output.
Rz = Resistance Needed
Zo = Zero Offset in Volts (Step 6)
Example: In this example, our maximum CSG110 output would be 5 VDC
E = Excitation (Step 4)
(Corresponding to 2mV/V) and our Minimum CSG110 output would be 2.5 VDC
(Corresponding to 0 mV/V). Thus the total Span would equal 5 – 2.5 = 2.5 VDC
Br = Bridge Resistance of your sensor
4)
Now that you know what you would like your output to be (Step 2)
Rz = -Br (
⎟
Zo
⎟
- 0.5E) / (2Zo)
and you know the span range (Step 3) you must vary the Input
Jumpers and Excitation Jumpers to create this range. The
Example:
formula for this is:
Rz = -350 (
⎟
0.01
⎟
- 0.5(5)) / (2*0.01) = 43575
Thus, a resistor of 43.575K ohms is necessary to offset the zero
.
CSG110 Output Span = (Rated Output x Excitation) / Input
Range
8)
Now that the input range and excitation have been determined
and the resistance necessary for a zero shift of 2.5V is known, all
The two known values are the:
you need to do is complete the setup.
CSG110 Output Span
, which refers to your desired span (Step 3)
First make sure that you have soldered together the correct input
Rated Output
which refers to the output of the sensor (Step 1)
range jumper (4.0) and excitation jumper (5.0). Next take your
43.5K ohm resister and solder it in to the ISI location on the
The two variables are the:
CSG110 board (Shown below).
Excitation
, this can either be 5 VDC or 10 VDC (See ‘SELECTION
OF EXCITATION VALUE’)
ADJUSTING THE SPAN
Input Range
, this can either be 0.5, 1.0, 1.5, 2.0, 3.0, or 4.0 (See
The input jumpers vary from 0.5, 1.0, 1.5, 2.0, 3.0, and 4.0. This
‘INPUT VALUE ADJUSTMENT’)
allows for a large variety of input ranges. However, it sometimes
happens that the Rated Output from the sensor is not exactly 2.0mV/V
Vary the
Excitation
and
Input Range
until you get a CSG110
or 3.0mV/V. The CSG110 does have a
-20 to 4.5 % of R.O.
adjustment
Output Span that is equal to (or vary close to) you span
range so a
sensor with an output close to that of the input ranges will
(calculated in Step 3). Sometimes it is helpful to make a chart to
work fine.
However, when the Rated Output of the sensor falls between
keep track of the span values.
Excitation
Input Value
10
5
0.5
40.0
20.0
1
20.0
13.3
10.0
6.7
1.5
2
10.0
5.0
3
6.7
3.3
4
5.0
2.5
two of t
he input ranges it is necessary to use a resistor to adjust the
output of t
he sensor.
To adjust the output of the sensor when using the CSG110 all you
have to do is disconnect the ETR (Excitation Thru) jumper and connect
a resistor to the RSPSET location (pictured). Use the equation below
to calculate the value of the resistor needed.
Rs = Span Resistance Needed
Br = Bridge Resistance
Do = Desired output
Ao = Actual Output
Rs = (Ao/Do – 1)*Br
Example:
Rated Output (Step 1) = 2mV/V,
Span = 2.5 VDC (Step 3)
Example:
Excitation can be 5 or 10 VDC
Input Range can be 0.5, 1.0, 1.5, 2.0, 3.0, 4.0 mV,
Br = 350 ohm
Do = 2.0 mV/V
Ao = 2.5 mV/V
*The formula above was used to fill in the table to the right
.
Rs = (2.5/2.0-1)*350 = 87.5 ohms.
As you can see in the table, using a 5 VDC excitation and the 4.0 mV jumper will
give you an output span of 2.5. Thus, set your jumpers accordingly.
You can also visit our span calculator at
www.futek.com/spancalc.asp
x
*Any of the spans that come out to be more than 10VDC (Span limit of the
to find the span resistance value.
CSG110) will not work. Therefore they are crossed off in the table.
FUTEK ADVANCED SENSOR TECHNOLOGY
, INC.
* 10 Thomas * Irvine, CA 92618 * Tel: (949) 465-0900 * Fax: (949) 465-0905 * www.futek.com
FUTEK ADVANCED SENSOR TECHNOLOGY
, INC.
* 10 Thomas * Irvine, CA 92618 * Tel: (949) 465-0900 * Fax: (949) 465-0905 * www.futek.com
