Frequently Asked Questions
What is 8, 10 & 12 bit resolution?
These numbers (8, 10 and 12 bits) refer to the XR440 Data
Logger's adjustable measurement
resolution (XR5 Data Loggers have fixed 12 bit
resolution). Pace Data Loggers convert analog signals (Temperature, Pressure, etc) into
digital numbers. A digital number is a series of ones and zeros. An 8 digit (or
8 bit) digital number can represent 256 different values. A
resolution of 8 bits means that the measurement range for each
channel is divided into 256 parts. 10 bit resolution divides the
measurement range into 1024 parts, and 12 bit resolution divides
the measurement range into 4096 parts. The higher the number of
bits, the finer the resolution, the higher the sensitivity
(ability to measure small signal changes), and the more space
required in memory to hold one reading. See XR440 Specifications to compare
memory capacity and accuracy for 8, 10, and 12 bit resolution.
What resolution should I use?
In general, we suggest you select 12 bit resolution (in the XR440 software's Setup
screen). The Setup screen displays the Total Log Time which is determined by the
number of ON channels, the Sample Rate, and the selected Resolution. For a
given setup (number of ON channels and Sample Rate), if a longer Total Log Time is desired, and a reduced sensitivity
(resolution) is acceptable for your application, then you could select a lower
Resolution, which would increase the Total Log Time.
How is memory allocated in the XR440 Data Logger?
The memory is evenly divided by the number of channels you
have turned ON (in the software's Setup screen)
What is the function of the XR440's 'E' terminal?
The E terminal provides 5 Vdc excitation (power) to any connected sensor that requires 5
Vdc power (for example, the TRH-100 Temperature/Humidity Probe, and all Pressure Sensors.
Can the XR440's E terminal be used to power other non-Pace sensors?
In some cases, yes. The E terminal provides a precise 5 Vdc at a
maximum current of about 20 milliamps. If you are logging at a fast sample
rate (1Hz - 200Hz) the E terminal output is a constant 5 Vdc. However, if
you are logging at a standard rate (2 secs or slower), the E terminal output is
pulsed for a short time just prior to the XR440 sampling its inputs (either
0.025 secs or 0.1 secs, depending on the selected Setup). This is done to
insure a long battery life. So even if your non-Pace sensor's power
requirement is less than 20ma at 5 Vdc, it also needs a very fast "warm-up time" in
order to work with the XR440.
Does using power from the XR440's E terminal reduce battery life?
If the total current drawn from the E terminal is less than 5 milliamps,
battery life will be 2 - 3 years under normal use. Drawing 10 ma from the
E terminal will reduce battery life to about 18 months, and 20 ma from the E
terminal will reduce battery life to about 1 year. If Real
Time Mode is used constantly, battery life will be cut roughly in
half (see next question).
What happens to the XR440's battery life if Real Time Mode is constantly active?
If you use Real Time Mode constantly, battery life will be cut approximately
in half using the default 19.2k baud rate speed. Using slower speeds (9600
or lower) reduces battery life further and is not recommended if Real Time Mode
is in constant use.
For linear sensors, how does the XR440's High / Low scaling compare to Slope /
Offset scaling?
High / Low scaling is similar to Slope / Offset scaling. With High /
Low scaling, the High value is the equivalent reading for a sensor output of 5 V, and the
Low value (and Offset value) is the equivalent sensor reading if its output is 0 volts.
High / Low scaling can be converted to Slope / Offset Scaling as follows:
Slope = (High Value + |Low Value|) / 5
Offset = Low Value
Note: |Low Value| is the absolute value of the Low Value; if the Low Value is a negative number, simply remove the negative sign, if it is positive, use the number as it is.
Slope / Offset scaling can be converted to the XR440's High / Low scaling as follows:
High Value = ( Slope * 5 ) + Offset
Low Value = Offset
Can Pace Pressure Sensors read in any unit of pressure?
Yes. Scaling values for the default unit of pressure are listed on the body of each sensor
and are also listed in the XR440 Software's Help system, and in the XR5-SE's User's Guide.
These scaling values can be converted to read in any desired pressure unit (bar, kPa, etc).
A web-based calculator is provided to convert the scaling values of any Pace Pressure Sensor to read in a different unit of pressure.
XR440 Calculator XR5 Calculator