Yokogawa YVP20S - Manual (Page 83)

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<9. CONFIGURATION SERVICES>
IM 21B04C50-01E
9.2.3 Limit Switch Threshold
The Limit switch thresholds apply to the Discrete Input (DI) block setpoints.
● Threshold Low
The threshold for the low limit switch that communicated by the DI block.
● Threshold High
The threshold for the high limit switch that communicated by the DI block.
9.2.4 Fault Control
● Error Band
The position deviation limit to start deviation timer of Time 1 and Time 2.
Set this value to a value that is exceeded only in abnormal performance.
● Time 1
The position deviation time limit to show the block alarm. A negative value turns off this
function. Set this value greater than the stroking time.
● Time 2
The position deviation time limit to trigger the failsafe action. Enter “-1” to disable this
function. A negative value turns off this function. Use of the Time 2 failsafe may result in
unwanted process shutdowns.
WARNING
Use the Time 2 failsafe only for a critical process that must be forced into its failsafe position
if the valve is unable to respond to its position setpoint after a reasonable time delay. Do
not set the error band to a value that is too small. If Time 2 is used, it must be longer than
the valve stroking time. A Time 2 value that is too small will result in nuisance failsafe
behavior.
9.2.5 Servo Alarms (I/P Module Operating Point Fault Control)
This function is applicable only to the device revision 4 or higher (or the device revision 2 or
higher when the software download functions are available).
● Servo Warning High
If the operating point of the I/P module is more than this value, the timer that measures the
time after the I/P module operating point error starts.
● Servo Warning Low
If the operating point of the I/P module is less than this value, the timer that measures the
time after the I/P module operating point error starts. Input a value that is the same as or
less than that for Servo Warning High.