Trend Block Example

You can chain together Trend blocks to trend more than 80 values. The following steps illustrate the design of the following chain:  

To chain Trend blocks together:

  1. Add a Trend block to the process database.
  2. Enter the name of the second Trend block in the Next Block field of first Trend block.
  3. Add the second Trend block to the process database.
  4. Enter the name of the first Trend block followed by the F_INP field into the Input field of second Trend block.

You could continue and add a third Trend block to become part of a chain similar to the one identified in the following table. This table shows the key fields to complete.

Block Type

Block Name

INPUT Field

Next Block field

AVG/COMPRESS Field

Analog Input

AI1

N/A

TR1

N/A

Trend

TR1

AI1.F_CV

TR2

5

Trend

TR2

TR1.F_INP

TR3

5*

Trend

TR3

TR2.F_INP

AO1

5*

Analog Output

AO1

N/A

blank

N/A

* NOTE: You can enter any number from 1 to 255 into the Average Compress field; however, when you chain multiple Trend blocks together, the value you enter for the second and subsequent Trend blocks should be the same as the first Trend block's. If the values in the Average Compress fields do not match, the visual pattern of trended data displayed in the iFIX WorkSpace is different and possibly confusing to operators.

If the Input field of trailing Trend blocks is blank, these blocks trend the value passed to them. For example, using the values from the preceding table, if the Input fields of TR1 and TR2 are blank , all three Trend blocks would trend the same 80 values sent by AI1 instead of a chain of 240 values.