Basic rules of PLC ladder diagram - Database & Sql Blog Articles

Ladder diagram is one of the most commonly used programming languages ​​for plc programming. It is widely used in system design of engineering sites. To better use ladder language, some basic rules of ladder diagram are introduced below. 1, no contact on the right side of the coil

Each logical line in the ladder diagram is arranged from left to right, starting with the contact and the left bus, and ending with the coil, the function command and the right bus connection.

2, the coil can not be reused

In the same ladder diagram, if the coil of the same component is used two or more times, then the front output coil is invalid for the external output, and only the last output coil is valid. Therefore, the double coil output is generally not present in the program.

3, the contact level is not vertical

The contacts should be drawn on a horizontal line. If drawn on a vertical line, it is difficult to identify its logical relationship with other contacts.