NSD servo system.
A73CPU (P21/R21) -S3 dedicated.
Relay output interface circuit of PLC
Working process: when the internal circuit output digital signal 1,
There is a current flowing through, the relay coil has a current, and then the normally open contact is closed,
Provide load current and voltage A2ACPUP21 Programming Manual .
When the internal circuit outputs a digital signal 0, there is no current flowing through it,
The relay coil does not have a current, and the normally open contact is broken off,
A current or voltage that is disconnected from the load A2ACPUP21
It is through the output interface circuit to the internal digital circuit into a signal to make the load action or not action.
When the programmer input programinto the user program memory,
Then CPU according to the function of the system (the system program memory to explain the compiler),
Translate the user program into PLC internally recognized by the user to compile the program A2ACPUP21 Programming Manual .
I/O points is an important indicator of PLC.
Reasonable selection of I/O points can not only satisfy the control requirements of the system,
And the total investment of the system is the lowest A2ACPUP21 Programming Manual .
The input and output points and types of PLC should be determined according to the analog quantity and switch quantity of the controlled object,
Generally an input / output element to take up an input / output point.
Taking into account the future adjustment and expansion,
In general should be estimated on the total number of points plus the amount of spare 20%~30%.
The following describes the centralized control system I/O points of the estimate. Input and output points: 2048 points.
Input / output data points: 2048 points.
Program capacity: 30K.
Basic command processing speed (LD command) s:1.0.
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.
Only when the program is scanned, the new state is read.
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.
Centralized output mode.
There exist input / output hysteresis phenomena, i.e., the input / output response delay.
User program storage capacity: it is a mmeasure of how much the user application can store the number of indicators A2ACPUP21 Manual.
Usually in words or K words as units. 16 bit binary number is a word,
Every 1024 words are 1K words. PLC to store instructions and data in words.
General llogical operation instructions each account for 1 words A2ACPUP21 Manual. Timer / counter,
Shift instruction accounted for 2 words. Data operation instructions for 2~4.