Hello everyone,
I have a fundamental question about typical A/B PLC rung scans.
Consider the following:
A B
---][-------()---
From what I have understood it means the following:
IF A = true THEN
B = true;
ELSE IF A = false THEN
B = false;
END IF;
So that means that each rung actually implies two statements:
one when A will be true and the other when A is false.
So if B is true above this rung somewhere and when the processor reaches this rung and A is false, IT WILL SET B TO FALSE.
Please tell me if I am wrong because this is an important point. I have a background in higer level programming (C, VB.NET, C#) and in those languages, true and false conditions have to be explicitly defined. False conditions are not evaluated so if A is false then nothing will happen to B, if it set to 1 above this rung, B will remain 1. If B is 0, it will still be 0. It seems that this is a very big and fundamental difference between ladder language programming and higher level programming.
Please advise.
Thanking you all,
Bobby1234
I have a fundamental question about typical A/B PLC rung scans.
Consider the following:
A B
---][-------()---
From what I have understood it means the following:
IF A = true THEN
B = true;
ELSE IF A = false THEN
B = false;
END IF;
So that means that each rung actually implies two statements:
one when A will be true and the other when A is false.
So if B is true above this rung somewhere and when the processor reaches this rung and A is false, IT WILL SET B TO FALSE.
Please tell me if I am wrong because this is an important point. I have a background in higer level programming (C, VB.NET, C#) and in those languages, true and false conditions have to be explicitly defined. False conditions are not evaluated so if A is false then nothing will happen to B, if it set to 1 above this rung, B will remain 1. If B is 0, it will still be 0. It seems that this is a very big and fundamental difference between ladder language programming and higher level programming.
Please advise.
Thanking you all,
Bobby1234