When using the CTU (Count Up) function, a user may want the ability to start counting from a pre-determined value instead of having the counter start from zero.
This may occur if the logic restarts and the counter goes back to zero but RemoteConnect does have another function block CTU_Retained that counts upward from zero and sets an output ON when the counter reaches a specified limit. This DFB operates similarly to the CTU function block except the counter value is retained over program initialization provided there is a T_SPx70_UDINT object variable connected to the CV_Retained input/output pins.
Alternatively, there may be other reasons that a user would want to manually adjust the value in a logic counter. The DFB CTUD has separate triggers for either upwards or downwards counting which would be suitable for keeping track of a stack size that can go up and down over time.
The user could use the UpTrigger boolean input to increment the counter like a normal CTU function block. They may or may not even be interested in using the DownTrigger input.
The input PresetValue would be the new desired value that the user wishes to force the counter to and the boolean input Load would be used to trigger when to have the CountValue jump to the PresetValue .
