PLC working mode
As we all know, the working mode of PLC is:
Cyclic scanning: from the beginning to the end of the program, from the left end to the right end, progressive scan, repeating!
A line of words seems simple and well understood, but there are still a lot of errors in actual programming, because the foundation is not solid enough. How does the cyclic scan of the PLC work? We can refer to a two-way circuit to introduce.
Two-way circuit
What is a two-way circuit, say a simple example:
One button lights up and goes off: the first time you press the button, the light bulb is on, the second time you press the button, the light bulb goes out, this is the divide-by-2 circuit!
The implementation of the divide-by-two circuit is very much. In order to better reflect the theme of this issue (the working mode of the PLC), the basic logic instructions will be used for writing. See the following figure for details; among them: button - X0, lamp - Y0.
PLC cycle scanning process
A thousand words, not as detailed as a picture:
It doesn't matter if you don't understand, there are decomposition actions below.
The following four figures are used to explain the process of pressing the button for the first time.
- The light is on.
Figure 1, the program status before the button is pressed
Figure 2, button press, the first scan cycle of the PLC
Figure 3, the button is pressed to the end, (not yet released), the PLC starts the second scan cycle (assuming the second one, the scan cycle is very fast)
Figure 4, program status after releasing the button
The following four figures are used to explain the second press of the button to the release process.
- The light goes out.
Figure 1, the program status before the second press of the button
Figure 2, the second press of the button, the first scan cycle of the PLC
Figure 3, the button is pressed to the bottom for the second time, (not released yet), the PLC starts the second scan cycle
Figure 4, program status after releasing the button
For diifferent USB types, micro USB, mini USB, etc. The logo, color or shape can all made as customers' requirement. With more than ten years of experience and capabilities assisting our customers in various industry, ETOP would be confident to be your qualified AVL and reliable manufacturing partner.
Related Products:usb cable,micro usb cable,usb data cable.
Data Cable,Data Flexible Electrical Magnetic Cable,Usb Data Cable,Micro Usb Cable,USB Connector
ETOP WIREHARNESS LIMITED , https://www.wireharness-assembling.com