Loading a PS/FC/AC 800F using altered objects where the processing order of the blocks has not been configured correctly
- Observing the processing order of blocks
The effect mentioned above does not occur provided the processing order is observed during configuration on a FBD sheet.
Loading an FBD sheet marked with an alteration arrow using changed objects can have unexpected effects on the variables on the sheet (e.g. outputs) if the block order on the loaded FBD sheet is not observed.
- Incorrectly configured processing order of blocks on an FBD sheet
An FBD sheet is altered and then plausibilised. The alteration arrow in front of the node of the FBD sheet shows that this content is loaded on the PS, FC or AC800F when loading is carried out using changed objects.
In this procedure, the internal variables as they are called are set to 0. Internal variables are for instance the connecting lines between the blocks, i.e. not named variables which are configured as inputs or outputs. The first time the program computes, these variables are given values in the processing order.
If, however, the processing order on the sheet is not correct, i. e. a block with processing number 1 accesses a variable created from a block with processing number 5, the loading algorithm also treats this variable as an internal variable, i. e. it sets it to 0 for one cycle. This can have undesired effects including the one-time resetting of outputs.