ABB BB510(DC5256) 3BSE001693R2 modular

Description

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Quantity available: 1

The colour：New

Warranty: 12 months.

Lead time: 3 days.

Payment: T/T 、 Western Union.

When the PLC is running, it completes the control task by executing the user program that reflects the control requirements, and many operations need to be performed, but the CPU cannot perform multiple operations at the same time. It can only perform one operation at a time in a time-sharing operation (serial work) manner, one by one in sequence. As CPU’s operation processing speed is very fast, from a macro perspective, the results appearing outside the PLC seem to be completed simultaneously (in parallel). This serial working process is called PLC scanning working mode.

When the user program is executed in the scanning mode, the scanning starts from the first program. Without interruption or jump control, the user program is executed one by one in the sequence of program storage until the program ends. Then scan from the beginning and run repeatedly.

The working principle of PLC scanning is obviously different from that of electrical control. The electrical control device adopts the hard logic parallel working mode. If the coil of a relay is powered on or off, all normally open and normally closed contacts of the relay will immediately act at the same time no matter where they are in the control circuit; The PLC adopts the scanning mode (serial mode). If the coil of a soft relay is connected or disconnected, all its contacts will not act immediately and will not act until the scanning reaches this point. However, due to the fast scanning speed of PLC, there is usually no difference between the I/O processing results of PLC and electrical control devices.

BB510(DC5256)