UMSITRPDS3-1
On-Line Operation
November 2010
6-7
6.2.1 Cancel Pushbutton Disable and Write Protection
A pushbutton disable (LA, LO, LS, or L) can be entered locally or from the HART Communicator. To
enable the pushbuttons, press and hold the M pushbutton for at least 5 seconds.
Another pushbutton disable (LL) can be entered from the Communicator. This disable must be canceled
using HART. See Section 6.4.9 to cancel the LL disable.
6.2.2 Set/Adjust Zero and Full Scale
Zero and full scale can be set or adjusted from the magnetic pushbuttons. Modes 2 and 3 provide access.
Both forward and reverse acting characteristics are accommodated.
6.2.2.1 Theoretical Relationships
Setting Zero and Full Scale
First, specify the desired zero and full scale analog output currents, typically 4 mA and 20 mA
respectively. Operating process pressures are then specified: p
min
and p
max
, for minimum and maximum
operating pressures. When specifying these input pressures, always refer to the rating plate for model
number, measuring span, and other performance related information.
Apply the input pressures and set the output currents using the local magnetic pushbuttons or the HART
Communicator. Input pressures can be supplied by the process or by test equipment. Set zero first and
then set full scale, since setting zero does not affect the span and setting full scale does not affect zero.
The relationship between the measured pressure and the resulting current output is linear, except when a
square root output characteristic is selected. The output current for a linear relationship can be calculated
using the following equation.
mA
mA
p
p
p
p
I
4
16
min
max
min
+
∗
−
−
=
An example of the use of this equation is given below.
1.
Given: a transmitter with a measuring range of 0 to 232 psi. The operating range is to be 29 to 203
psi.
2.
Apply 29 psi to the transmitter. Press the M (mode) pushbutton to set the transmitter to mode 2. Set
the zero by pressing the
(
and
'
pushbuttons simultaneously for about 2 seconds. An output current
of 4 mA is then set.
3.
Apply 203 psi. Press the M pushbutton to set the transmitter to mode 3. Set the full scale by pressing
the
(
and
'
pushbuttons simultaneously for about 2 seconds. An output current of 20 mA is then set.
4.
Calculate the output current for other input pressures. Apply the desired pressure and check the output
current against the calculated value.
I = output current
p = input pressure for I
p
min
= minimum operating input pressure (MA in leporello)
p
max
= maximum operating input pressure (ME in leporello)
Summary of Contents for 7MF4033 series
Page 48: ...Model 275 Universal Hart Communicator UMSITRPDS3 1 November 2010 2 26 ...
Page 86: ...Installation UMSITRPDS3 1 November 2010 4 34 ...
Page 152: ...Calibration and Maintenance UMSITRPSD3 1 November 2010 7 20 ...
Page 158: ...Circuit Description UMSITRPDS3 1 November 2010 8 6 ...
Page 197: ......
Page 198: ......
Page 200: ...Model Designations and Specifications UMSITRPDS3 1 November 2010 9 42 ...
Page 204: ...Glossary UMSITRPDS3 1 November 2010 10 4 ...
Page 208: ...Appendix A Online Configuration Map UMSITRPDS3 1 11 4 November 2010 ...
Page 216: ...Appendix C Elevation and Suppression Correction UMSITRPDS3 1 13 4 November 2010 ...