Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 64)

<4. COMMISSIONING OF pH/ORP>
4-10
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
On the Redundant system, when a sensor (Sensor 1) of the 1st module fails, the output is
automatically switched to the output of the 2nd module.
After repairing the Sensor 1, manual reset of redundant system is necessary to return to the
output of 1st module from the output of the 2nd module.
mA mA
mA
R(1) R(2) R(1)
F0503_2.ai
Return mA to Sensor1?
Yes
No
Reset redundant system
Sensor 1
Display
Sensor 2
Alive Alive
Alive Alive Alive
Dead Dead
Alive
Sensor 1 is dead.
(automatic)
Repair sensor
Redundant system
restart (manual)
If sensor 1 fails, the
output is automatically
switched to the sensor-2
value.
This display is the
example when
“Redundant” is
selected as a
process parameter.
Even if a fault on the sensor 1 is
recovered automatically after
fault detection, the output will not
be switched back automatically
and the sensor 2 value will
continue to be output.
After repairing sensor 1, reset the backup made
by the redundant system. This enables the
sensor 1 value to be incorporated in the output.
On the Reset redundant system, selection of
“Yes” makes the output return to the output of
the 1st module.
Output setup
mA Output
Configure Hold
Reset redundant
Figure 4.4 Redundant system
Setup
Select one of the output methods: Linear and Table.
Linear: Set the 0% and 100% values.
Table: This allows the configuration of an output curve by 21 points (5% intervals).
(The 0% and 100% values must be entered.)
Burn
Select the designated output in case of a fault from among Off, Low, and High. See “4.4 Error
configuration” to set the output.
Off: Output depends on the measured value.
Low: Output is fixed to 3.6 mA
High: Output is fixed to 22.0 mA.
Damping time
This is the time taken for a response to a step input change to reach 90% of the final value
(attenuation time). Set this time in sec.
l Simulate
When this function is selected, an output of the instrument will be a fixed current value set in % of
the output span. The output span range is -2.5% to 112.5% (3.6 mA to 22.0 mA).
When “Simulate” is selected, regardless of hold setting, the output is always simulated value.