Yokogawa EXA ISC202 2-wire Conductivity Transmitter/Analyzer - Manual (Page 79)

IM 12D06A03-01E
Appendix 2-7
12-4-2. Commissioning Mode Settings
12-4-2-1 Output Range Setting
Refer to Sec. 5-2-1
1. What does output range setting involve?
When linear output (linear relationship between conductivity and analog output) is selected, the meas-
urement range corresponding to the 4 to 20 mA DC analog output range must be set.
The default measurement range is 0 to 1,000 mS/cm.
The display autoranges up to 1999 mS/cm.
Zero suppression and non-linear output characteristic may be set (see Sec. 5-2).
2. Setting zero-suppression for output range
For setting ranges with zero suppression, you must specify two points:
• Conductivity corresponding to 0% of range (4mA DC)
• Conductivity corresponding to 100% of range (20mA DC)
The conductivity value corresponding to 0% of range must be no greater than 90% of the value corre-
sponding to 100% of range.
Example: To set range 10 to 100 mS/cm
Default 0% setting is 00.0mS/cm.
To change this to 10.0mS/cm, press the
>
key.
Next press four times until the units display is flashing to change the units.
Press the >
key four times until the units display changes to display 10.0 mS/cm.
Press ENT to confirm.
Default 100% setting is 1000 mS/cm. Press four times until the units display is flashing.
Press the
>
key until the units display changes to display 100.0 mS/cm.
Press ENT to confirm.
Setting non-linear output
With the ISC202 Inductive Conductivity Transmitter you can define a 21-step non-linear-characteristic
(transfer function) output table ― to provide an analog output proportional to concentration, for example.
If you define such a table, then output range setting is disabled/invalid. Refer to Sec. 5-3-3 and 5-3-4 for
21-step-table setting details. You can also display concentration in weight% (rather than conductivity in
mS/cm) as described in Sec. 5-3-5.
NOTE:
Output range 4mA and 20mA points can correspond to conductivity values in the range 0 to1999
mS/cm, but the following restrictions apply:
*1 1999 mS/cm ≤ | ( 0% setting ) - ( 100% setting ) | ≤ 100 μS/cm
*2 Smaller of settings ≤ 90% of larger of settings
12-4-2-2 Setting Hold Functions
Refer to Sec. 5-1-5 and 5-2-2
1. What are HOLD functions?
HOLD functions temporarily hold the output signal, and are typically used to maintain output when the
sensor is removed from the measured solution, i.e. to prevent alarms and prevent disturbance to control.
HOLD functions are set in Commissioning Mode.
You can set H.LST (HOLD LaST value before entering HOLD, e.g. maintenance, mode) ― this is typi-
cally used when the transmitter is connected to a recorder ― or H.FIX (HOLD predetermined fixed value,
e.g. so that control and alarms are not adversely affected).
The default value is for HOLD to be disabled (OFF).
2. How do HOLD functions operate?
Output HOLD status is set as follows:
Under Maintenance Mode (press the MODE key), or Commissioning Mode (press the ½ key)
Under calibration
You can also turn on HOLD manually as described in Sec. 5-2-2.
When reverting from Calibration, Commissioning, or Maintenance modes to Measurement mode, the
user must select whether HOLD should be turned OFF or remain ON.