Skip to Content

Wiki source code of 18 Step control instructions

Last modified by Wecon on 2025/09/03 21:03
Hide last authors
Wecon 1.1 1 = **6.18.1 STL, RET instructions** =
2
3 **Instruction description**
4
5 (% class="table-bordered" %)
6 |**Name**|**Function**|**Device**|**Step**
7 |STL|STL programming start instruction|S|1
8 |RET|STL programming end instruction|~-~-|1
9
10 Step Control (STL) is controlled by several operating procedures (S0, S1……Sn).
11
12 Step Control method's feature is that after taken into considerations for each control step and divided the complex procedure into successive steps, it greatly reduces the interdependence between each step and the complexity involved in programming.
13
14 **Program example**
15
16 Example 1
17
18 (% style="text-align:center" %)
19 [[image:7-17 Step control instructions_html_761d86411de91841.jpg||class="img-thumbnail" height="378" width="300"]]
20
21 In example 1, RET will be omitted between each step procedures. Therefore, it will seem a RET is shared by several STL. When STL is programmed and RET procedure is not, error message will appear.
22
23 Example 2
24
25 (% style="text-align:center" %)
26 [[image:7-17 Step control instructions_html_bbca4de39842d0f5.jpg||class="img-thumbnail" height="441" width="300"]]
27
28 State transfer could only use the SET instruction, couldnot use OUT instructions.
29
30 Example 3
31
32 (% style="text-align:center" %)
33 [[image:7-17 Step control instructions_html_696157f1b5a11163.jpg||class="img-thumbnail" height="437" width="400"]]
34
35 Time relay T could be reused, but the adjacent two states couldnot be reused using the same time relay.
36
37 **Note for use**
38
39 * STL~-~--RET instructions couldnot be used in sub-programs.
40 * When transition is happening from current status (S0) to next status (S1), the actions under the two scouldning cycle conditions will both be executed; when the next scouldning cycle is being executed, current status (S0) will be reset by the next status (S1), and the actions under the current status (S0) will not be executed. All OUT components' inputs will be interrupted.
41 * Generally speaking, RET will be omitted between each step procedures. Therefore, it will seem a RET is shared by several STL. When STL is programmed and RET procedure is not, error message will appear.