Input unit (encoder, pulse generator) (NSD servo system)
Each scanning process. Focus on the input signal sampling. Focus on the output signal to refresh.
Input refresh process. When the input port is closed,
Program in the implementation phase, the input end of a new state, the new state can not be read A9GT-50LT Manual A9GT-50LT User's Manual.
Only when the program is scanned, the new state is read A9GT-50LT
A scan cycle is divided into the input sample, the program execution, the output refresh.
The contents of the component image register are changed with the change of the execution of the program.
The length of the scan cycle is determined by the three.
CPU the speed of executing instructions.
Time of instruction.
Instruction count.
Due to the adoption of centralized sampling A9GT-50LT Manual A9GT-50LT User's Manual.
Centralized output mode.
There exist input / output hysteresis phenomena, i.e., the input / output response delay.
PLC selection with the development of PLC technology, more and more types of PLC products,
Function is becoming more and more perfect, and its application is more and more extensive.
Different series of different models of PLC has different performance, applicable occasions also have different emphasis,
Price also has a greater difference A9GT-50LT Manual A9GT-50LT User's Manual. Therefore PLC selection,
Under the premise of meeting the control requirements,
Should consider the best performance to price ratio, a reasonable choice of PLC.
System program memory for storing system program,
Including management procedures, monitoring procedures, as well as the user program to do the compiler to compile the process of interpretation.
Read only memory. Manufacturers use, content can not be changed, power does not disappear. CC-Link master / slave station.
PLC is the use of " sequential scanning, and constantly circulating " way to work.
That is, in the operation of CPU, PLC according to the user according to the control requirements of the coexistence of the user in the memory of the program,
According to the instruction sequence number (or address number) for periodic cyclic scan, such as no jump instruction,
From the first instruction to the user program execution sequence one by one, until the end of the program,
And then return to the first command, start the next round of the new scan, in the process of each scan,
Also complete the sampling of the input signal and the output status of the refresh and other work.
PLC is the use of " sequential scanning, and constantly circulating " way to work.
That is, in the operation of CPU, PLC according to the user according to the control requirements of the coexistence of the user in the memory of the program,
According to the instruction sequence number (or address number) for periodiic cyclic scan, such as no jump instruction,
From the first instruction to the user program execution sequence one by one, until the end of the program,
And then return to the first command, start the next rround of the new scan, in the process of each scan,
Also complete the sampling of the input signal and the output status of the refresh and other work A9GT-50LT Manual A9GT-50LT User's Manual A9GT-50LT Manual A9GT-50LT User's Manual.