Precision machining HS code checks

List of contents of this article:

• 1,Precision machining HS code checks What are the I/O control methods
• 2,< A href='#Operating System IO Mechanism' title='Operating System IO Mechanism'>Operating System IO Mechanism
• 3, I/O Device Management< /A>
• 4, viv What is the o system
• 5, Linux system I/O operation and zero copy
• 6, What is the module of et200sp

What are the I/O control methods

[Answer]: I/0Control mode: program I/0 mode, interrupt drive 1/0 control mode, DMAI/0 control mode, 1/0 channel control mode.

This question examines the control mode of I/O equipment. There are 4 common I/O device control methods: program I/O, interrupt drive I/O, direct memory access I/O control, and I/O channel control.

There are four I/O control methods, namely: circular test I/O method (polling method); using I/O test instructions to test equipment. If the device is not busy, the input or output command will be executed; if the device is busy, the I/O test instruction will continue to test the device until the device is idle.

I/O channel control mode. Channel (CHannel) is also known as peripheral processor and input and output processor, which is relative to CPU. It is a processor. It can also execute instructions and procedures by instructions, but the instructions executed by the channel are instructions related to external devices.

Operating system IO mechanism

1. io is divided into memory io, disk io and network io. It is generally considered to be the latter two. In order to reduce the number of io times, improve cache utilization, and protect kernel space, the operating system is empty Page cache 2) memory address register (MAR, memory address register) is designed in the room.

2. Mmap makes applications and operating systems shareKernel buffer, the application directly reads and writes on the kernel buffer without data copying. In the Linux system, the operation is replaced by calling mmap().

3. The computer system is hierarchical, which is composed of multi-level hierarchical structure. In terms of function, computer systems can be divided into five levels. The first level is the microprogram design level, also known as the hardware level; the second level is the general machine level, also known as the machine language level; and the third level is the operating system level, which is implemented by the operating system program.

4. When the process needs data, write the control words that allow startup and interruption to the device control status register, and start the device for input operation. (2) The process abandons the processor and waits for the completion of the input. The operating system process scheduler schedules other ready processes to occupy the processor.

I/O device management

1. I/O control methods mainly include program query method, interrupt method, DMA method and I/O channel Control method. The program query method is also known as the program polling method, which uses the user program to directly control the input/output operation between the host and the external device.

2. First, open the settings of vivo mobile phone.Secondly, click More Settings or More Security Settings. Finally, find the option about mobile phone or device manager in it, and click enter to view the device information of the machine.

3. I/O equipment is all input and output equipment that manages and controls computers. A large number of peripherals, that is, I/O devices, are configured in modern computer systems. According to their different working methods and classifications, character devices, also known as human-computer interaction devices.

What is vivo system

1. The system of vivo mobile phones is FuntouchOS and OriginOs. FuntouchOS FuntouchOS is a smartphone operating system developed by vivo based on Android. Since its release in October 2013, it has always adhered to user experience as the core and "simplicity. Fun. The concept of "wisdom" is design-oriented.

2. vivo smartphones adopt the Funtouch OS system, which is deeply developed based on the Android system. The specific system version of vivo smartphone can be viewed by entering the mobile phone settings - more settings - about the mobile phone (some models also need to click the version information). Specific operation steps (take X9 as an example): Find the setting icon on the mobile phone desktop.

3. vivo system is an operating system developed by Chinese smartphone manufacturer vivo. It is a deeply customized version based on the Android operating system.The goal of the vivo system is to provide a smoother, more convenient and beautiful user experience, while ensuring the stability and security of the system.

Linux system I/O operation and zero copy

Simply put, zero copy is a technology that prevents CPU from copying data from one fast storage to another.

The system I/O operation using DMA requires 4 context switches between kernel space and application space, 2 CPU data copies and 2 DMA data copies. The difference between Mmap memory mapping and standard I/O operation is that when the application needs to access data, there is no need to copy data between the kernel buffer and the application buffer.

Next, we use a very common application scenario of Java: sending files in the system to the remote end (the process involves: files on the disk - memory (byte array) - transmission to the user/network) to expand the traditional I/O operation in detail and realized through zero copy. I/O operation.

sendfile is only suitable for copying data from the file to the socket, limiting its scope of use. Linux introduced the splice system call in version 17, which is used to move data in two file descriptors.

For sendfile system calls with DMA copy collection function, the copy between kernel buffers can also be reduced again.

what is the module of et200sp

. ET200-SP is a multi-functional expansion module that can expand up to 7 modules to control the control system and DCS system. ET200-SP is an intelligent expansion module for 120, 300 and 1500 extensions.

Don't. Et200sp is a service module. When ordering, it comes with a base unit with the interface module. It is a set, so there is no need to order it separately. This product is mainly used in network construction and network connection, and is a terminal network server.

First of all, ET200SP is a distributed I/O system, while S7-200 is a classic stand-alone PLC. ET200SP CAN COMMUNICATE WITH THE MAIN CONTROL PLC THROUGH PROFINET OR PROFIBUS TO ACHIEVE DISTRIBUTED CONTROL.The S7-200 can only communicate with other devices through serial port or network communication.

ET200SP is a remote input/output module launched by Siemens, which can communicate with PLC through different communication interfaces. If the communication interface of ET200SP is replaced, it needs to be re-regured to ensure that the new communication interface can work properly.

et200sp version is different and the firmware needs to be updated. ET200SP is an on-site distributed I/O provided by Siemens, which can expand different submodules on ET200SP distributed I/O. After the firmware update of the I/O module, it is used for functional expansion to adapt to different versions.

The interface module is used to connect the distributed et200sp and the controller or dp master station, and realize data exchange with the io module through the backboard bus.Siemens et200mp is a scalable and highly flexible distributed io system used to connect process signals to the central controller through the fieldbus.