Input and output points: 2048 points.
Input / output data points: 8192 points.
Program capacity: 30K.
Basic command processing speed (LD command) s:0.15.
Integral type: the PLC components are installed together or a few pieces of printed circuit board,
And together with the power supply installed in the casing to form a single overall called the host or the basic unit, small, ultra small PLC using this structure MITSUBISHI AJ71LP21GE Reference Manual AJ71LP21GE
Modular: PLC is the basic components of a separate module.
Medium and large PLC used this way. Easy maintenance.
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 MITSUBISHI AJ71LP21GE Reference Manual .
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 MITSUBISHI AJ71LP21GE Reference Manual .
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 measure of how much the user application can store the number of indicators.
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 logical operation instructions each account for 1 words. Timer / counter,
Shift instruction accounted for 2 words. Data operation instructions for 2~4. SI/QSI/H-PCF/ wide H-PCF optical cable double loop PC (control station / common station) / remote I/O network (remote master station).
Switch volume control is designed to,
According to the current input combination of the switch quantity and the history of the input sequence,
So that PLC generates the corresponding switching output,
In order to make the system work in a certain order.
So, sometimes also known as the order control.
And sequential control is divided into manual, semi-automatic or automatic.
And the control principle is decentralized, centralized and hybrid control three.
The length of time required to execute the instruction, the length of the user''s program, the type of instruction, and the speed of the CPU execution are very significant,
Generally, a scanning process, the fault diagnosis time,
Communication time, input sampling and output refresh time is less,
The execution time is accounted for the vast majority of.
The response time of PLC is the interval between the time of the change of the external output signal of the PLC annd the time of the change of the external output signal which is controlled by it,
Lag time, this is the time constant of the input circuit,
The time constant of the output circuit, the arrangement of the user statement and the usse of the instruction,
The cycle scan mode of PLC and the way of PLC to refresh the I/O and so on AJ71LP21GE Manual AJ71LP21GE Manual .
This phenomenon is called the I/O delay time effect.