# FC 65 - Digital Sum with Gain

This function code computes a weighted sum of four boolean inputs using the following equation:

Output = S5<S1> + S6<S2> + S7<S3> + S8<S4>

It can be used to initiate a control action based on the number of boolean inputs that have a status of logic 1. These inputs could represent the status of pumps, valves, motors, etc. Outputs:

 Blk Type Description N R S5 + S6 + S7 + S8

Specifications:

 Spec Tune Default Type Range Description S1 N 0 I Note 1 Block address of S2 N 0 I Note 1 Block address of S3 N 0 I Note 1 Block address of S4 N 0 I Note 1 Block address of S5 Y 1.000 R Full Gain parameter for S6 Y 1.000 R Full Gain parameter for S7 Y 1.000 R Full Gain parameter for S8 Y 1.000 R Full Gain parameter for

NOTES:

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

65.1   Applications

Figure 65-1 shows how to use function code 65 to determine flow rates from a digital indication of pump status. In the example, each operating pump provides a constant flow rate of 20 gallons per minute. An operating pump provides an output of logic 1. Specifications <S1> through <S4> provide the pump status inputs while S5 through S8 are pump flow rates. When pumps one, three and four are operating, the output is as follows.

Output          = S5 <S1> + S6 <S2> + S7 <S3> + S8 <S4>

=  20 gal (1)  +  20 gal (0)  +  20 gal (1)  +  20 gal (1)

min               min                  min                min

=  60 gal

min

Function code 65 can also be used for binary to real conversion. Binary to real conversion changes digital signals to analog signals (i.e., counters). Specifications <S1> through <S4> provide the binary inputs. Specifications S5 through S8 weight the inputs to achieve the desired real output. For example:

<S1> and <S4> = logic 1

<S2> and <S3> = logic 0

S5 = 1.0

S6 = 2.0

S7 = 4.0

S8 = 8.0

Output = S5 <S1> + S6 <S2> + S7 <S3> + S8 <S4>

= 1.0(1) + 2.0(0) + 4.0(0) + 8.0(1)

= 9.0 