Xylem H-5223 - Manual (Page 33)

offset to be edited. An example of using the offset could be for a temperature sensor that has
a 0 to 5 volt output that represents a -40 to +60 degree C range respectfully. First calculate a
slope as follows:
Slope = (Max Degrees - Min Degrees) / (Max Volts - Min Volts)
Slope = (60 - (-40)) / (5 - 0) = 100 / 5 = 20
Now look at the basic equation and fill it in with known data. The slope is now known, and
we know that at 0 volts the temperature is -40 degrees.
Temperature = slope * volts + offset (Basic equation)
-40 = 20 * 0 + offset (Basic equation with known values added)
Notice that 20 * 0 is zero so that part of the equation is dropped, and the offset is left.
-40 = offset
This is the value that would be entered into the system for this type of sensor.
D - Differential Mode
Channels 1 and 2 can be configured as a differential input. When the differential mode is
‘On’ the value reported for channel 1 will be the difference between channel 1 and 2.
Channel 1 is the positive input of the differential pair. Channel 2 should not be used as a data
source for logging or for GOES but if it is used it will return the same value as channel 1.
3.5.3 G - Generic SDI-12 Options
The following shows what the “SDI-12 Options” screen looks like and is used to test SDI-12
sensors. SDI-12 sensors have a set of standard commands. This menu allows for the standard
commands to be sent by simply pressing a single key. Sensors may also have an extended
command set for specific options related to that sensor. There is also an option to edit an
extended command and send it to the addressed sensor.
--- SDI-12 Command Mode ---
T - Test Address: 0
A - Acknowledge
I - Identify
V - Verify
M - Measure
D - Data Retrieval
S - Send Extended
E - Edit Extended: XRS
P - +12Vx Mode: Always On
Enter Option >
H-5223
Remote Operation (Menu Mode) 3-11