JF-1A Conductivity Sensor
A440-009
Page 53 of 56
FEBRUARY 2009
key, the JF-1 will respond with the words “OPEN
MODE”.
6)
Read the current offset value TRL, enter the request
“TRL” the unit will return “TRL=-20, where “-20”is
the current setting, as we want to change the lowest
value to b 0˚C we need to change TRL to = 0, enter the
comment “TRL=0”, store using the ***E command.
7)
Read the current full scale value of the current output
TDAC, enter the request “TDAF” the unit will return
“TDAF=83.5 (typically), where “83.5”is the current
setting, one can assume the full scale range is 60, note
the TDAF value represents a “scaling” factor and will
not exactly be equal to the range.
8)
As we are changing the range lower by ~20% to 0˚C to
50˚C full scale we can make an initial assumption the
TDAF value will need to be lower, i.e. TDAF=65.5.
This value is temporarily entered into TDAF by
sending “TDAF=65.5”.
9)
To test this value we need only to set conductivity to
our desired full-scale value by sending “Temp=50” to
the JF-1 unit.
10)
Read the Digital Voltage Meter output that should be
connected across either the 250 or 100-ohm sense
resistor. The voltage should equal 5.00 +/- 0.01 volt
for the 250-ohm resistor, or 2.00 +/- 0.005 volts for the
100-ohm sense. If this is not attained TDAF needs to
adjusted, increase the value of TDAF if the voltage is
high, decrease the value if the voltage is low. Repeat
Step 6 then Step 7 until the correct voltage (current is
attained).
(Note the unit will not automatically update
the output after a change in TDAF is made, the user
must re-send the “Temp=50” each time an
adjustment is made to change the current output.)
11)
After steps 6 - 10 are complete the user should now
check the “low end of the range to ensure the slope