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.
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. Therefore PLC selection,
Should consider the best performance to price ratio, a reasonable choice of PLC.
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.
Input and output points: 480 points.
Program capacity: 7K step.
Basic command processing speed: 4.4 ~ 5.6us.
Power supply: input DC5V output 2A DC24V/.
Modular: PLC is the basic components of a separate module.
Medium and large PLC used this way. Easy maintenance.
User program storage capacity: it is a measure of how much the user application can store the number of indicators A70PL-S3.
Usually in words or K words as units
A70PL-S3 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.
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 A70PL-S3.
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 A70PL-S3.
It is through the output interface circuit to the internal digital circuit into a signal to make the load action or not action. Output points: 16 points.
Voltage: DC12/24V.
OFF leakage current: 0.1mA.
Output type: transistor output (type sink).
Response time: 2ms.
8 points / a common end.
20 point terminal station.
With heat protection.
With the surge absorber.
With short circuit protection.
The number of I/O thyristor DC motor control required tube DC motor speed control system is the main form of DC speed regulation,
The thyristor rectifier unit is used to supply power to the DC motor.
PLC control of the DC drive system, the input of the PLC in addition to the main signal outside the signal,
We need to consider the switching signal, the fault signal transmission device, brake signal and fan fault signal.
The output of the PLC mainly consider the speed command signal positive 1~3 level, 1~3 level, allowing reverse switching signal and brake open signal etc..
In general, a reversible DC drive system controlled by PLC is approximately 12 input points and 8 output points,
An irreversible DC drive system requires 9 inputs and 6 output points.
MITSUBISHI PLC is the main product in the production of MITSUBISHI motor in Dalian.
It uses a kind of programmable memory for its internal storage procedures,
Execute logic operation, sequence control, timing, counting and arithmetic operations, user oriented instruction,
And through digital or analog input / output control of various types of machinery or production process.
Control solenoid valve required I/O points by the action principle of the solenoid valve ccan be known,
A single coil solenoid valve with PLC control to 2 input and 1 output,
A double coil solenoid valve requires 3 inputs and 2 outputs,
A button needs an input; a light sensitive switch needs 4 or 2 inputs,
A signal lamp needs 1 output, band switch,
Several bands are required for several inputs,
In general, a variety of position switches are required to take up 2 input points A70PL-S3 A70PL-S3.