Ny-Series Instructions Reference Manual (W560 - Omron NY532-5400 Reference Manual

2 Instruction Descriptions
Bit strings
Enable OK
H
X
L
EPS
Q OK
QH OK
QL OK
Function
The LimitAlarm_** instruction monitors the input value to see if it is between the lower limit set value
and the upper limit set value. The LimitAlarm_** instruction outputs an alarm if the input value is below
the lower limit set value or above the upper limit set value. Use this instruction in temperature control,
e.g., to monitor the process temperature.
Input value X is monitored while Enable is TRUE. If the value of X exceeds the value of upper limit set
value H, upper limit alarm QH changes to TRUE. If the value of X goes below the value of lower limit set
value L, lower limit alarm QL changes to TRUE. If the value of either QH or QL is TRUE, the value of
alarm output Q is TRUE. The values of X, H, L, and hysteresis EPS are continuously updated while
Enable is TRUE.
If Enable changes to FALSE, the alarm is reset. When the alarm is reset, Q, QH, and QL change to
FALSE.
The data types of H, X, L, and EPS must be either REAL or LREAL. The name of the instruction is
determined by the data types of H, X, L, and EPS. If the name of the instruction is LimitAlarm_LREAL,
the data types of H, X, L, and EPS are all LREAL.
Operation of Upper Limit Alarm QH
The value of upper limit alarm QH changes as shown below. You can set the hysteresis to prevent
hunting in the limit alarm.
• If Input value X > Upper limit set value H, then QH is TRUE.
• If Input value X < Upper limit set value H − Hysteresis EPS, then QH is FALSE.
Upper limit set value H
Upper limit alarm QH
2-744
Must be same data type as H.
Must be same data type as H.
Must be same data type as H.
Input value X
TRUE
FALSE
Integers
OK

NY-series Instructions Reference Manual (W560)

Times, durations,
dates, and text
strings
OK
Hysteresis EPS
Time