ChangeSelect Function Block

The Change Select function block checks whether the input values have changed compared to the last DDC cycle. If the value has changed, it sets the corresponding Boolean output to "true" for 1 DDC cycle. More than one output can be "true" if numerous changes are detected.

Figure 1: ChangeSelect - Function Block

Figure 2: ChangeSelect - Property Sheet

 

Figure 3: ChangeSelect - Logic Diagram

Inputs

Input Name

Description

Enable

It is a Boolean point that is used to enable the block.

If it is set to "false", there is no change and all outputs remain "false". If it is set to "true", activates the change detection.

In A

If this input changes from the previous DDC cycle, Out A becomes "true".

In B

If this input changes from the previous DDC cycle, Out B becomes "true".

In C

If this input changes from the previous DDC cycle, Out C becomes "true".

In D

If this input changes from the previous DDC cycle, Out A becomes "true".

Table 1: Inputs of ChangeSelect Function

Output

Output Name

Description

Out A

If In A changes from the previous DDC cycle, Out A becomes "true". The output is "true" only in the DDC cycle where the change is detected.

A change to "null" or from "null" is a valid change.

Out B

If In B changes from the previous DDC cycle, Out B becomes "true". The output is "true" only in the DDC cycle where the change is detected.

A change to "null" or from "null" is a valid change.

Out C

If In C changes from the previous DDC cycle, Out C becomes "true". The output is "true" only in the DDC cycle where the change is detected.

A change to "null" or from "null" is a valid change.

Out D

If In D changes from the previous DDC cycle, Out D becomes "true". The output is "true" only in the DDC cycle where the change is detected.

A change to "null" or from "null" is a valid change.

Table 2: Output of ChangeSelect Function

Parameter

Parameter Name

Description

Out Save

Master Sync Enabled : If you set it to "true" the last output will be set as output for one cycle after the controller restarts. The application can use it to return to the same state before the controller restart.

Out: To enable or disable the Out Save feature.

Out Equal Zero:To enable or disable the Out Equal Zero feature.

Table 3: Parameter of ChangeSelect Function

Examples 

If Block Enable is "true", change in any of the input value the concern output is set to "true" for a short while.

Figure 4: Example - ChangeSelect Function Block

 

Refer to General Description for general information about IRMN4 Function Blocks.