Chapter 8 Logic Instructions
8-109
FC
RAND is used to generate a random number.
Parameters
Meaning
Description Valid range
In Reserved Input Reserved
Depends on the data type of
the variable that the input
parameter is connected to.
Out
Random
number
Output Random number
Depends on the data type of
the variable that the output
parameter is connected to.
Boolean
Bit string Integer
Real
number
Time, date
String
BOOL
BYTE
WORD
DWORD
LWORD
USINT
UINT
UDINT
ULINT
SINT
INT
DINT
LINT
REAL
LREAL
TIME
DATE
TOD
DT
STRING
In1
●
Out
●
Note:
The symbol ● indicates that the parameter is allowed to connect to the variable or constant of the data
type.
Function Explanation
RAND is used to generate a random number and the result is output to Out, within the range
0~32767.
The input value does not have any effect on the random number to generate. But the value must
be input for In.
To get the random number within a specific range, users just need perform the MOD calculation
over the generated value and get the remainder. For example, the random number between 0
and10 can be generated by writing the program RAND(0) MOD10.
Precautions for Correct Use
The input variable is not allowed to omit. An error will occur during the compiling of the software if
the input variable is omitted. But the output variable is allowed to omit.