Is there any Scan difference between Control Module and Function Block ?
Control modules are having default input Pins of 4 or 16.
Where as Function Block is user defined for Input Pins.
Will this affect the Cyclic Load on the Controller ?
Ex: I have 5 inputs that are connected to an AND Block.
In case of Control Module I need to use 16 Pin Block, but where as in Function Block I can define 5 pin Input and connect.
Where as Function Block is user defined for Input Pins.
Will this affect the Cyclic Load on the Controller ?
Ex: I have 5 inputs that are connected to an AND Block.
In case of Control Module I need to use 16 Pin Block, but where as in Function Block I can define 5 pin Input and connect.
Asked 2 months ago
Voted best answer
1
No, you need to use 2 * AND(4) blocks ...
However, "AND" is a poor example to choose. This is a system function and is very efficient. There is no parameter copying required for an AND instruction. Bear in mind that FBD (and also IL, SFC and LL ) is just structured text behind the programming interface. They're all the same thing. However, ST has slightly less "overhead" because the programmer can control exactly how much code is written and where parameters are copied.
The differences between Function Blocks and Control modules have very little to do with the number of input or output terminals. The main consideration is whether values have to be "copied" when passed to a Function Block or "Passed By Reference" when used in a Control module. You can force a parameter to use a Reference address by setting the property declaration to "by_ref".
See the manual AC800M Configuration, Section 1, "Function Block Execution" for a description of the differences between Functions and Control modules. Understanding this information in detail can help you write significantly more efficient code.
However, "AND" is a poor example to choose. This is a system function and is very efficient. There is no parameter copying required for an AND instruction. Bear in mind that FBD (and also IL, SFC and LL ) is just structured text behind the programming interface. They're all the same thing. However, ST has slightly less "overhead" because the programmer can control exactly how much code is written and where parameters are copied.
The differences between Function Blocks and Control modules have very little to do with the number of input or output terminals. The main consideration is whether values have to be "copied" when passed to a Function Block or "Passed By Reference" when used in a Control module. You can force a parameter to use a Reference address by setting the property declaration to "by_ref".
See the manual AC800M Configuration, Section 1, "Function Block Execution" for a description of the differences between Functions and Control modules. Understanding this information in detail can help you write significantly more efficient code.
Answered 2 months ago
Add new comment