Beginners PLC ladder diagram programming, should follow certain rules, and to develop good habits. Following is a brief overview of PLC ladder diagram programming you need to follow the rules.
Trapezoidal steps are started in the bus left and finally the right bus (usually saves not painting, painted bus left only). Is a combination of contacts on the left side of each row, driven logic coil condition and represents a logical result can only pick on the right side of the coil on the bus. Contact coil on the right are not allowed.
Second, the contact should be painted on the horizon should not be painted on the vertical line.
Three, should not use double coil output. On the same ladder in the coils of the same component twice or more, and are known as dual output coil or coils of reuse. Dual-ladder diagram Starter coil output likely to commit one of the problems. Double coil output, only the last coil is available, while the front coil was invalid. This is decided by the PLC scanning.
Four parallel series, contact way should be placed at the left of the ladder diagram (left to right light principle), series parallel, parallel path of contacts should be placed on top of the ladder diagram (light weight). To do so, simple, so as to reduce the scanning time of instruction, which is especially important for large programs.
PLC ONE 