Allen-Bradley LOGIX 5000 Reference Manual page 22

Chapter 1 Process Control Instructions
22
ALARM Structure
Input Parameter
EnableIn
In
HHLimit
HLimit
LLimit
LLLimit
Deadband
ROCPosLimit
ROCNegLimit
ROCPeriod
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Data Type Description
BOOL Enable input. If false, the instruction does not execute and outputs
are not updated.
Default is true.
REAL The analog signal input.
Valid = any float
Default = 0.0
REAL The high-high alarm limit for the input.
Valid = any real value
Default = maximum positive value
REAL The high alarm limit for the input.
Valid = any real value
Default = maximum positive value
REAL The low alarm limit for the input.
Valid = any real value
Default = maximum negative value
REAL The low-low alarm limit for the input.
Valid = any real value
Default = maximum negative value
REAL The alarm deadband for the high-high to low-low limits
Valid = any real value
Default = 0.0
REAL The rate-of-change alarm limit in units per second for a positive
(increasing) change in the input. Set ROCPosLimit = 0 to disable
ROC positive alarming. If invalid, the instruction assumes a value of
0.0 and sets the appropriate bit in Status.
Valid = any real value
Default = 0.0
REAL The rate-of-change alarm limit in units per second for a negative
(decreasing) change in the input. Set ROCNegLimit = 0 to disable
ROC negative alarming. If invalid, the instruction assumes a value of
0.0 and sets the appropriate bit in Status.
Valid = any real value
Default = 0.0
REAL Time period in seconds for calculation (sampling interval) of the
rate of change value. Each time the sampling interval expires, a
new sample of In is stored, and ROC is re-calculated. Instead of an
enable bit like other conditions in the analog alarm, the rate-of-
change detection is enabled by putting any non-zero value in the
ROCPeriod.
Valid = 0.0 to 32767.0
Default = 0.0.
0.0
0.0
0.0