CPCI-680 |Motorola / Force Computers| CPU Module

Description

CPCI-680 |Motorola / Force Computers| CPU Module

For users, when writing user programs or selecting devices, it is necessary to be clear about the three stages introduced below, which are the principles of the user program execution process.
CPCI-680 adopts a centralized processing method, which means that the input scanning signal, user program execution, and output refresh are all processed in a centralized batch manner.
In this stage of input scanning, the PLC reads in all input signals on the input terminals in a scanning manner and stores the input signals in the input image area, and the input image memory is refreshed. During the program execution phase and output refresh phase, the input image memory is isolated from the outside world, and its content remains unchanged until the input scan phase of the next scan cycle, when the input signal is re read is refreshed. It can be seen that when executing programs and processing data, PLC does not directly use the input signals from the site at that time, but instead uses the data input into the image area during this sampling.

If the input device can form a closed loop at the CPCI-680 input end, the internal input relay corresponding to the input end number is saved as “1”, which is equivalent to the relay coil conducting. During program execution, the corresponding contact action for this number; If the input device can open the input, the internal input relay corresponding to the input terminal number is saved as “0”, which means that the relay coil is not conducting, and the contact corresponding to this number does not act during program execution. If the PLC is in a non input scanning stage and the input device status outside the CPCI-680 changes, the internal input relay will not change either. It will have to wait until the next input scanning stage to refresh based on the current input status. So, for input signals that are less than ten milliseconds, they often cannot be collected.