FC 6 - High / Low Limiter

This block limits the output signal to a range that lies between a specified high and low limit. The output equals the input <S1> when the input is between the limits. Output N equals the high limit when the input is higher than the high limit and equals the low limit when the input is lower than the low limit.

 

 

Outputs:

Blk

Type

Description

N

R

Output value equals input value unless the input

reaches the low or high limit. Then, the output value

assumes the value of the limit.

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

5

I

Note 1

Block address of Input

S2

Y

9.2E18

R

Full

Value of High Limit

S3

Y

-9.2E18

R

Full

Value of Low Limit

 

NOTES:

1. Maximum values are: 9,998 for the BRC-100, IMMFP11/12 31,998 for the HAC

 

6.1 Applications

Figure 6-1 shows a limiter used to limit the bias range. The flow transmitter input range is zero to 300 gallons per minute.  The bias value for this example is +20 gallons per minute but the high limit should not exceed 320 gallons per minute. By using the configuration shown, the 20 gallons per minute bias is achieved without exceeding the maximum limit.

 

 

Figure 6-2 shows function code 6 used to limit the input to a divider function. This is necessary in many applications to prevent unprocessable quotients (i.e., divide by zero), especially when <S2> is very small.