GSK 980TC3 Series, Manual

Page: 17 / 226

Chapter 2 Sequence Program
5
Ⅰ
Programming
Chapter 2 Sequence Program
The operating principle is different with the common relay, because the PLC sequence
controlling is carried out by the ladder diagram Lad Edit.exe compiling.
And therefore, it is better to thoroughly understand the sequence controlling principle when
designing the PLC sequence programming.
2.1 Performance Process of Sequence Programming
In the general relay controlling circuits, each of them can be simultaneously operated. When the
relay A is operated in the following figure, the replay D and E can be operated (when the contactor A
and B are closed) at the same. Each replay in the PLC sequence control is operated in turn. The
relay D is operated before relay A, and then the relay E operates (refer to the following figure).
Namely, each relay is operated based upon the sequence of the ladder diagram (compiling
sequence).
A
A
B
C
D
E
Fig. 2.1 (a) Circuit illustration
The differences between the relay circuit and PLC programming operation are shown below in the
Fig. 2.1 (b) and Fig. 2.1 (c).
A
A
C
B
C
Fig. 2.1 (b)