(1) input/output relays, auxiliary relays, timers, counters, the contacts of the device can be used repeatedly without complex programs to reduce the number of contacts.
(2) the ladder each row from left buses start coil terminate in the right bus. Contacts should not be placed right of the coil
(3) in addition to stepping outside of any coil, timers, counters, advanced directives cannot be directly connected to the bus left.
(4) in the program, do not allow the same number of coil output twice (double coil output).
(5) the bridge circuit is not allowed.
(6) the program sequence should be top down, written from left to right. In order to reduce the number of program execution steps, procedures should be left to the right small large small.
(7) input devices with normally open contact
(8) experience in PLC programming design method
In the traditional relay–contactor control and PLC on the basis of typical control circuit, based on accumulated experience to translate, modify and improve, and get the final program.
(9) the common PLC typical control circuit
PLC ONE 