FC 9 - Analog Transfer

This function selects one of two inputs depending on boolean input <S3>. The output of function code 9 equals the input determined by the state of input <S3>. There are two time constants to provide smooth transfer in both directions.

 

Outputs:

Blk

Type

Description

N

R

Output equals one of two possible inputs

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

5

I

Note 1

Block address of first input

S2

N

5

I

Note 1

Block address of second input

S3

N

0

I

Note 1

Block address of transfer signal:

0 = output equals <S1>

1 = output equals <S2>

S4

Y

0.000

R

Full

Transfer to input 1 time constant/sec

S5

Y

0.000

R

Full

Transfer to input 2 time constant/sec

 

NOTES:

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

 

9.1 Explanation

Specification S3 is the block address of the transfer signal that selects which input (<S1> or <S2>) transfers to the output. If <S3> is a logic 0, then <S1> will be transferred to the output. If <S3> is a logic 1, <S2> will be transferred to the output.  When the transfer block changes the input selected, the output level changes to the new input level exponentially over a

period of five time constants when the transfer time constant (S4 and S5) is set to a value other than zero. After five time  constants, the output tracks the selected input.

 

Specifications S4 and S5 are time constant terms. They specify the time required for the previous output value to reach 63.2 percent of the present input value. The output will essentially match the new input value after five time constants have passed. To calculate S4 or S5 so that the output equals the input in a certain number of seconds (t), use the following equation:

 

 

 

 

For example, if the required output must match the <S1> level 30 seconds after a transfer, and match the <S2> level in 15 seconds after a transfer:

 

9.2 Applications

Figure 9-1 shows how function code 9 can be used as an analog memory. In this example the output tracks <S1> when the <S3> digital input is a logic 0. The output value holds at its last level when the <S3> input is a logic 1.

 

 

Figure 9-2 shows how function code 9 can be used as a manual to automatic transfer switch. When <S3> of function code 9 equals 0, the auto signal for the M/A block equals the analog input (<S1>) of function code 9. When <S3> of function code 9 equals 1, the auto input signal tracks the output of the M/A station.