FC 66 - Analog Trend

The analog trend function code is part of the Symphony distributed trending package. It performs initial data compression for operator consoles and open access systems at the module level.

 

Trend data can be gathered in two ways, normal or fast, depending on the desired resolution. Specification S3 selects the trend resolution. Normal trending mode gathers trend data every 60 seconds. Fast trending is every 15 seconds.

 

Specification S2 selects the trend mode. Over the collection period each value collected is the sample, mean, minimum, maximum or sum of the input value <S1>.

Output data consists of the last value saved.

 

 

Outputs:

Blk

Type

Description

N

R

Last value saved

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

5

I

Note 1

Block address of analog input

S2

N

1

I

0 - 4

Trend mode:

0 = sample

1 = mean

2 = minimum

3 = maximum

4 = sum

S3

N

0

I

0 or 1

Trend resolution2:

0 = normal

1 = fast

 

NOTES:

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

2. Fast trending requires a higher amount of module utilization than normal trending. Specification S3 cannot be changed during the on-line configuration mode.

 

66.1  Explanations

 

66.1.1 Specifications

 

S1 – BLKADR

Block address of the analog input to be trended.

 

S2 (Trend mode)

Sets the trend mode during the collection period (S3). Each value collected is the

sample, mean, minimum, maximum, or sum for the point.

0 = sample; current point saved every 15 or 60 seconds

1 = mean; arithmetic mean value of all points over the trending interval

2 = minimum; minimum point  value over trending interval

3 = maximum; maximum point value over trending interval

4 = sum; sum of all values collected over trending interval

 

S3 (Trend resolution)

Sets the trend interval.

0 = normal; every 60 seconds

1 = fast; every 15 seconds

NOTE: Fast trending requires a higher amount of module utilization than normal trending.

 

 

66.2 Applications

 

To trend values, configure both an analog exception report and a trend block for each point trended. Figure 66-1 shows a sample analog trending configuration. Figure 66-2 shows a sample digital trending configuration. The block outputs go to the communication highway and have assigned tag names in the operator interface station. Both outputs must be configured for each point for display purposes.

 

To create a trend database and a tag database, refer to the human system interface configuration instruction. These instructions have sections titled Trends and Tag Database that will provide the necessary instructions to create the trend and tag databases.