14
The Ethernet Connection is an option and will be installed only if specifically ordered. It is
a 10MHz TCP/IP port that allows the user to program the recorder remotely, start or stop
recording and download real time data.
Refer to the separate manual that is supplied with the ethernet interface option.
2.3.6 USB Port (Option)
The USB Port is an option and will be installed only if specifically ordered. It is a serial
connection to a PC that allows the user to program the recorder remotely, start or stop
recording and download real time data.
Refer to the separate manual that is supplied with the USB interface option.
2.3.7 Cleaning
The unit may be cleaned by wiping with a soft cloth. The front panel and display / keypad
may be wiped with a slightly damp soft cloth containing soapy solution or a mild
detergent.
Do not use any lemon based (citric acid) product to clean the display /
keypad. NOTE: THE UNIT IS NOT WATERTIGHT.
2.4 INPUT
SCALING
The input to the recorder is often a standard process variable (e.g. voltage) rather than the
actual units being measured (e.g. pressure).
There are a number of custom conversions available in the unit to take care of special inputs
such as thermocouples and RTDs, which need special scaling and linearization. These are
preset in the unit and require no modification. There is also the capability to customize any
input variable that has a linear relationship to the measured variable. The relationship
between the required variable and the input variable must satisfy the constraint
y = mx + c
where
y
is the value to be displayed and recorded,
x
is the input variable (typically volts or
milliamps DC),
m
is the scale factor which defines the relationship between the input and the
displayed variable and is a constant (linear relationship), and
c
is a constant offset variable
that may be positive or negative.
This facility to scale the input is found in the ADVanced SETUP menu and is available to
each channel independently in dual channel units. Here the user can easily scale the input
and set the displayed units using three alphanumeric characters.
The scaling is achieved in the unit in the CHANnel X SETUP option (X = A or B) in the
ADVanced SETUP menu. First set the displayed LO SCALE, which may be positive, negative
or zero. Then set the displayed HI SCALE for the full-scale input. The unit will then
automatically compute the scale factor and offset.
Setting the engineering units is done in the same menu
location using the CHAN UNITS option to set the three
alphanumeric characters.
Let us assume we have an input from a pressure
transducer of 1 to 5 volts DC, corresponding to real
world units of zero to 250 PSI (Pounds per Square Inch
of pressure). Assume we choose the 0 to 5 volt input.
The actual output span of the transducer is 4 volts, with
1 volt = 0 PSI and 5 volts = 250 PSI. This is equivalent
to 62.5 PSI per volt. The LO SCALE which is the "0" volt
5
4
3
2
1
0
0
125
250
-62.5
(OFFSET)
INPUT
VOLTS
PSI
Summary of Contents for Data Chart 1250
Page 1: ......
