11 PROCESS CONTROL INSTRUCTIONS
11.2 I/O Control Instructions
1201
11
■Range check (1)
• The instruction checks the range of the input value (E1).
If the input value (E1) goes beyond the upper or lower limits, an alarm is output.
*1 When ERRI or SEI of Disable alarm detection (INH) is set to 1, alarm output is disabled and therefore ALM SEA, BB2, and BB3 are set
to 0.
• Last value hold processing
When a range excess occurs (BB1 = 1) in the range check, whether to continue operation or terminate the S.IN instruction is
determined by whether SM816 is on or off.
■Input limiter (2)
The instruction sets the upper and lower limits for the input value (E1).
■Engineering value inverse transformation (3)
The instruction performs engineering value inverse transformation of the input limiter result (T1) according to the following
expression.
■Digital filter (4)
The instruction applies a digital filter to the input value (E1) according to the following expression. The digital filter is used to
reduce the effect of noise.
BW=T2+(last BW value-T2)
Range check Condition Range check result (alarm output)
BB2 BB3 BB1, SEA
Upper limit check E1 HH 1
*1
1
*1
E1 H0 0
H < E1 < HH Last value Last value
Lower limit check E1 LL 1
*1
1
*1
E1 L 00
LL < E1 < L Last value Last value
Condition Description
SM816 is off (not in hold mode) "Input limiter (2)" is performed even if a range excess occurs (BB1 = 1).
SM816 is on (in hold mode) If a range excess occurs (BB1 = 1), the following processing is performed to terminate the S.IN instruction.
• The last output value (BW) is held.
• Error information is stored in BB.
Condition Result (T1)
E1 NMAX NMAX
E1 NMIN NMIN
NMIN < E1 < NMAX E1
T2=(EMAX-EMIN)× +EMIN
NMAX-NMIN
T1-NMIN
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