5/2004 Manual for connection and operation of the EV-94 EB page 23 of 28
6. Offset- and slope-adjustment
The offset and slope-adjustment function can be used for compensating the tolerance of the used sensor,
resp. for vernier adjustment of the used transducer resp. transmitter.
Please note:
The settings of the offset- / slope-adjustment will be cancelled, when no button was pressed
for more than 60 sec. Changes you may have made already won‘t be saved and will be lost!
Please note:
The settings of the offset- / slope-adjustment and alarm-boundaries will automatically be reset to
factory default when any changes for the settings “InP”, “SEnS“ resp. “Unit“ had been made!
Hint:
The buttons 2 and 3 are featured with a ‘roll-function‘. When pressing the button once the value will be raised
(button 2) by one or lowered (button 3) by one. When holding the button pressed for longer than 1 sec. the
value starts counting up or down, the counting speed will be raised after a short period of time.
The device also features a ‘overflow-function‘, when reaching the upper limit the device switches to the lower
limit, vice versa.
-
Turn on the device and wait after it finished its built-in segment test.
-
Press button 3 > 2 sec. (e.g. with a small screwdriver).
The device will be displaying „OFFS“ (offset).
-
Use button 2 and button 3 for setting the desired zero point offset-value.
The input of the offset will be in digit resp. °C/°F.
The value that had been set will be subtracted from the measured value.
(see below for further information)
-
Press button 1 to validate your selection. The display shows “
OFFS
“ again.
-
When pressing button 1 again, the device will be displaying “
SCAL
“. (scale = slope)
-
Use button 2 and button 3 to select the desired slope-adjustment.
The slope adjustment will be entered in %. The value displayed can be calculated like this:
Displayed value = (measured value – zero point offset) * (1 + slope adjustment [% / 100]).
Example:The setting is 2.00 => the slope has risen 2.00% => slope = 102%.
When measuring a value of 1000 (without slope-adjustment) the device would display 1020 (with slope
adjustment of 102%)
-
Press button 1 to validate the selection of the slope-adjustment. The display shows “
SCAL
“ again.
Examples for offset- and slope-adjustment:
Example 1: Connecting a Pt1000-sensor (with an offset error depending on the cable-length of the sensor)
The device displays the following values (without offset- or slope-adjustment): 2°C at 0°C and 102°C at 100°C
Therefore you calculated: zero point: 2
slope:
102 – 2 = 100 (deviation = 0)
You have to set:
offset =
2
(= zero point-deviation)
scale
=
0.00
Example 2: Connecting of a 4-20mA-pressure-transducer
The device displays the following values (without offset- or slope-adjustment): 0.08 at 0.00 bar and 20.02 at 20.00 bar
Therefore you calculated: zero point: 0.08
slope:
20.02 – 0.08 = 19.94
deviation:
0.06
(= target-slope – actual-slope = 20.00 - 19.94)
You have to set:
offset =
0.08
(= zero point-deviation)
scale
=
0.30
(= deviation / actual-slope = 0.06 / 19.94 = 0.0030 = 0.30% )
Example 3: Connecting of a flow-rate-transducer
The device displays the following values (without offset- or slope-adjustment): 0.00 at 0.00 l/min and 16.17 at 16.00 l/min
Therefore you calculated: zero point: 0.00
slope:
16.17 – 0.00 = 16.17
deviation:
- 0.17
(=target-slope – actual slope = 16.00 - 16.17)
You have to set:
offset =
0.00
scale =
- 1.05
(= deviation / actual-slope = - 0.17 / 16.17 = - 0.0105 = - 1.05% )
Button 1 Button 2 Button 3
