6.2
Alternative 4-20mA scaling
USER En4
- 4mA input scaling without a live input - this calibration method can be used with
4-20mA inputs only. The instrument can be scaled for a 4-20mA input without a live input i.e. this
is an alternative method to the
CAL1
and
CAL2
method of scaling. To perform the first point
(
En 4
) scaling simply press the
^
and
v
buttons simultaneously when the
USER En4
function
is displayed. The display will now indicate a value. Use the
^
or
v
button to change this value
to the display value required for a 4mA input. Press the
F
button to accept changes or the
P
button to abort the scaling. If the scaling has been accepted the
CAL End
message should be
seen.
USER En20
- 20mA input scaling without a live input - this calibration method can be used
with 4-20mA inputs only. To perform the second point (
En 20
) scaling simply press the
^
and
v
buttons simultaneously when the
USER En20
function has been reached. The display will
now indicate a value. Use the
^
or
v
button to change this value to the display value required
for a 20mA input. Press the
F
button to accept changes or the
P
button to abort the scaling. If
the scaling has been accepted the
CAL End
message should be seen.
Note: the
USER En4
and
USER En20
method relies on the accuracy of the signal input. If the
sensor output is found to have an offset use the
CAL OFSt
function to correct for the offset. If
the slope of the sensor output is not correct then
CAL1
and
CAL2
methods will have to be used.
6.3
Offset calibration
CAL OFSt
- Calibration offset - the calibration offset is a single point adjustment which can be
used to alter the calibration scaling values across the entire measuring range without affecting the
calibration slope. This method can be used instead of performing a two point calibration when
a constant measurement error is found to exist across the entire range. To perform a calibration
offset press the
^
and
v
buttons simultaneously at the
CAL OFSt
function. A “live” reading
from the input will be seen, make a note of this reading. Press the
F
button, the message
SCLE
will now be seen followed by the last scale value in memory. Use the
^
or
v
button to adjust the
scale value to the required display value for that input. For example if the “live” input reading
was
50
and the required display value for this input was
70
then adjust the
SCLE
value to
70
.
Press the
F
button to accept changes or the
P
button to abort the scaling. If the scaling has
been accepted the message
OFSt End
should be seen. If the
ZERO RNGE Err
message is seen
refer to the
ZERO RNGE
and
CAL ZERO
functions.
6.4
Zero range
ZERO RNGE
- Zero Range - the zero range function allows a limit value to be set (in engineering
units) above which the display will not zero i.e. if a zero operation is attempted via the
P
button,
remote input or set zero function when the display value is greater than the zero range setting
the display will refuse to zero and give a
ZERO RNGE Err
message (note that the
CAL OFSt
function is also affected by the
ZERO RNGE
setting). For example if the zero range setting is
10
the instrument will only respond to a zero operation if the display reading at the time is between
-10
and
10
. If the zero range function is not required it can be set to
OFF
by pressing the
^
and
v
buttons simultaneously at this function. When switched off the instrument can be zeroed no
matter what the display value. Note that the instrument keeps track of the value being zeroed at
each operation, when the total amount zeroed from repeated operations becomes greater than the
zero range value the instrument will reject the zero operation and a
ZERO RNGE Err
message will
36 of
RM4IVMAN-2.1-0
Summary of Contents for RM4-IV
Page 8: ...8 of 49 RM4IVMAN 2 1 0...
Page 10: ...10 of 49 RM4IVMAN 2 1 0...
