YOKOGAWA Yew 80 Series, User Manual, Page: 22 / 66

4-4
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Reverse scaling (SCH1 < SCL1) is also possible.
A setting error occurs when SCH1 is set to equal SCL1.
• Bias:
A bias value (BIAS1) can be added to scaling values.
This allows error to be compensated when there is an error between the input value
and the indicated value.
Bias can be set within the range ±10% [(SCH1 - SCL1) x 0.1] of the scaling width.
The input value displayed on the display setter on the front panel (PV1 in the BRAIN
communications parameter) is the value after addition of bias.
● Explanation of Alarm detection block
In the following description, n is "1" for SKYD-10x, and "1" or "2" for SKYD-20x.
• Alarm detection n:
Performs alarm detection.
• ALMn ACTION: Alarm action
Direct .................. The alarm state is entered when the input value is at the preset
alarm set point or higher.
Reverse...............The alarm state is entered when the input value is at the preset
alarm set point or lower.
• SET POINTn: Alarm set point
• HYSTERESISn: Alarm hysteresis (See Figure 4-4.)
• ON DELAYn: Alarm ON delay
Sets the dead time until the alarm turns ON.
An alarm state is entered when the input value is in the alarm range for the duration
set at ON DELAYn.
If input returns to the normal range before the time set at ON DELAYn is reached, the
alarm does not turn ON.
• OFF DELAYn: Alarm OFF delay
Sets the dead time until the alarm turns OFF.
A normal state is entered when the input value is in the normal range for the duration
set at OFF DELAYn.
If input returns to the alarm range before the time set at OFF DELAYn is reached, the
alarm does not turn OFF.
• For ON DELAY/OFF DELAY, if you change the time during a delay, cancel the delay
operation, and restart operation with the set delay time.
• The alarm function does not work for 3 seconds after power ON.
● Relay output block
• RLYn ACTION: Alarm relay action
Energized at normal operation ............ The relay is energized when the alarm
detection result is a normal state.
De-energized at normal operation....... The relay is energized when the alarm detection
result is an alarm state.
• RLYn TEST: Relay action test
This function is for testing relay action.
Relays can be turned ON/OFF without influencing the currently alarm detection result.
Direction of alarm relay action: De-energized at normal operation (Factory-shipped settings)
ALMn Direction of alarm action Input value < Set point Set point < Input value
DIR Direct (high-limit alarm) Output relay de-energized Output relay energized
RVS Reverse (low-limit alarm) Output relay energized Output relay de-energized
Direction of alarm relay action: Energized at normal operation
ALMn Direction of alarm action Input value < Set point Set point < Input value
DIR Direct (high-limit alarm) Output relay energized Output relay de-energized
RVS Reverse (low-limit alarm) Output relay de-energized Output relay energized
4.2 Description of Functions