FC 34 - Memory

This function memorizes its previous output when both inputs are logic 0. Specification S1 is the set (S) input, and S2 is the reset (R) input. When both inputs have the value logic 1, the output assumes the override state specified by S4.

 

Specification S3 is the initial state flag. The value specified in <S3> will be the output after power up or a controller reset. Table 0-1 shows that the initial state depends solely on the value of <S3>. The values of <S1>, <S2> and S4 have no effect on initial output.

 

Table 0-2 shows the output for all other input combinations

 

 

Outputs:

Blk

Type

Description

N

R

Refer to Tables 34-1 and 34-2

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

Note 1

Block address of set input

S2

N

0

I

Note 1

Block address of reset input

S3

N

0

I

Note 1

Block address of initial state

S4

N

0

B

0 or 1

Override Value:

0 = reset

1 = set

 

NOTES:

1. Maximum values are: 9,998 for the BRC-100, IMMFP11/12 and31,998 for the HAC

 

 

 

34.1 Applications

 

This function code creates deadbands and retains signals. Figure 34-1 shows how to control a fan in the following manner:

  1. When air temperature reaches 21°C, the fan will turn on.

  2. When air temperature goes below 15°C, the fan will shut off.

  3. The fan will turn on when it receives a logic 1 signal, and it will turn off when it receives a logic 0 signal.

  4. Use a function code 12 (high/low compare) block to activate the <S1> (S) input when the air temperature reaches or exceeds 21°C. Use the same function code 12 block to activate the <S2> (R) input when air temperature is 15°C or lower. Figure 34-1 illustrates this configuration.