1. Mitsubishi plcThe ladder diagram program must conform to the principle of sequential execution, that is, execute from left to right and from top to bottom. If the circuit that does not conform to the sequence cannot be directly programmed, the circuit cannot be directly programmed.
2. Mitsubishi PLCEach line of the ladder diagram starts from the left busbar, and the coil is connected to the far right. In the relay control schematic diagram, the contacts of the relay can be placed on the right side of the coil, but the contacts are not allowed to be placed on the right side of the coil in the ladder diagram.
3. Mitsubishi PLCThe coil cannot be directly connected to the left bus, which means that the coil output must be conditional as a logic result. If necessary, it can be realized by using a break contact of an internal relay or an internal special relay.
4. Mitsubishi PLC The coil with the same number is used more than twice in one program, which is called double coil output. Double-coil output is easy to cause misoperation. At this time, the previous output is invalid, and only the last output is valid. However, the action of the corresponding contact of the output coil should be judged according to the output state before the logic operation. Because of the M1double-coil output, M1M1 FONT>The output changes with the last M1output,Y1with the first M1coil changes, whileM1 FONT>Y2With the secondM1 Output changes. Therefore, in general, double-coil output should be avoided as much as possible.
5. MitsubishiPLCSeries and parallel contacts in the ladder diagram There is no limit to the number of points and can be used unlimitedly.
6. Mitsubishi PLCExternal input/ Output relays, internal relays, timers, counters and other software The contacts of the components can be used repeatedly, and there is no need to deliberately adopt complex program structures to reduce the number of times the contacts are used.
7. Mitsubishi PLCTwo or more coils can be output in parallel.