337
Precautions PID data must be within prescribed ranges.
Note Refer to page 115 for general precautions on operand data areas.
Flags ER (A50003): PID data is outside of the allowable range.
The actual sampling period is two or more times the sam-
pling period that has been set.
The content of a*DM word is not BCD when set for BCD.
CY (A50004): The PID action is executed.
> (A50005): The MV after the PID action exceeds the upper limit.
< (A50007): The MV after the PID action is less than the lower limit.
5-24-2 LIMIT CONTROL: LMT(271)
(271)
LMT S C D
Ladder Symbol
Variations
↑LMT(271)
Operand Data Areas
D: Output word CIO, G, A, T, C, DM, DR, IR
C: First limit word CIO, G, A, T, C, DM
S: Input word CIO, G, A, T, C, #, DM, DR, IR
Description When the execution condition is OFF, LMT(271) is not executed. When the ex-
ecution condition is ON, LMT(271) controls output data according to whether or
not the specified input data (signed 16-bit binary) is within the upper and lower
limits. The contents of words C and C+1 are as follows:
C Lower limit data (minimum output data)
C+1 Upper limit data (maximum output data)
If the input data (S) is less than the lower limit (C), the lower limit data will be
output to D and the Less Than Flag (A50007) will turn ON.
If the input data (S) is greater than the upper limit (C+1), the upper limit data will
be output to D and the Greater Than Flag (A50005) will turn ON.
If the input data (S) is greater than or equal to the lower limit (C) and less than or
equal to the upper limit (C+1), the input data (S) will be output to D.
Upper limit (C+1)
Output
Input
Lower limit (C)
Precautions The lower limit (C) must be less than or equal to the upper limit (C+1).
Note Refer to page 115 for general precautions on operand data areas.
Flags ER (A50003): The upper limit setting is less than the lower limit.
The content of a*DM word is not BCD when set for BCD.
> (A50005): The input data (S) is greater than the upper limit (C+1).
EQ (A50006): The output data is all zeros.
< (A50007): The input data (S) is less than the lower limit (C).
N (A50008): The output data is a negative number.
(CVM1 V2)
PID and Related Instructions Section 5-24
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