With the current technological era, science & technology is developing strongly. Along with that, the industry is also developing constantly, especially in the field of industrial communication. Gradually, there are new communication standards, new industrial communication protocol standards, so that it is difficult to distinguish them. That’s why today plctop.com will learn about this knowledge with you.
USB (Universal Serial Bus)
USB is an acronym for Universal Serial Bus, which is a wired connection standard in computers. The USB standard is used for the purpose of connecting devices (phones, tablets, cameras, camcorders, music players or other industrial devices such as data collectors, remote I /O… with computers, the shape of USB is long, flat, square of all kinds.
Up to now, USB has 2 main types: USB 2.0 port and USB 3.0 port, USB 3.0 port is an upgraded version of USB 2.0. In theory, the data write speed of USB 2.0 is 60 MB / s, and USB 3.0 is 600 – 625 MB / s. It can be seen that the above speed is 10 times different, but in practice, this number is more modest, only about 3 times faster.
RS232 Communication
RS232 is a serial communication port and one of the industry communication standards, transmitting data in serial form. RS232 can be considered a legend, in the past years RS232 port was most commonly used with other names such as DB9 or COM. Serial communication is slower than parallel communication, but is commonly used for long data transmission because of its lower cost. Serial communication transmits data in a bit by bit fashion, while parallel communication transmits data in bytes (8 bits) or characters or bus at the same time. The baud rate of the commonly used RS232 port is: “9600, 14400, 28800, 33600”.
RS232 features:
+ RS232 is popular, easy to find, cheap.
+ Simple communication, support and compatibility with many devices
+ Good anti-interference ability and quite fast transmission speed
+The device can be powered through the RS232 . port
+ Easy to remove and install
RS422 Communication
RS422 is a serial data communication standard. The signal is transmitted over 2 wires, and the transmission speed depends on the transmission distance. With a line length of 40 feet (12m), the maximum transmission speed is 10 Mbits/s, 400 feet (122m) is 1 Mbits/s and 4000 feet (1219m) is 100 kbits/s. And at each output can connect and transmit data up to 10 receivers. However, the industry communication standard RS422 was almost completely superseded later.
RS485 Communication
RS485 can be considered as an upgraded version of RS422, with the difference being that RS485 allows connection and data transmission with up to 32 pairs of transceivers on the transmission line at the same time. Similar to RS422, the data rate of RS485 also depends and is proportional to the distance. With a line length of 40 feet (12m), the maximum transmission speed is 10 Mbits/s, 400 feet (122m) is 1 Mbits/s and 4000 feet (1219m) is 100 kbits/s.
Serial Port
Serial port or serial port is a concept used to define ports that operate on the principle of serialization, but with the topic of today’s article we only talk about common serial ports used in communication. industry such as: COM, RS232/RS422/RS485,.. And RS here stands for “Recommended Standard”, ie “recommended standards”. In communication technology, people can also classify according to the concept of simplex and duplex.
Simplex can simply be understood as one-way communication, data is only transmitted in one direction. That is, a device can only be a transmitter or a receiver. Single-pass communication is very efficient in transmitting large amounts of information to a large number of receivers.
Duplex communication overcomes the limitation of single-fair communication by allowing devices to act as transceivers. Data travels in both directions, thus allowing them to perform signal reception and control signal transmission at the same time. Through this, we can see that RS232, RS422 are full duplex communication, while RS485 is half-duplex operation.
MODBUS
Modbus is an industry communication standard developed by Modicon (Modicon now under Schneider) since 1979 to replace previous traditional communication standards. The way Modbus works is based on the principle of Master – Slave (receiver – sender of signals), to transmit data from terminals to PLC or SCADA.
Modbus has become a standard and popular industry communication standard because of: stability + simplicity + ease of use and free (an equally important factor). Devices that only need to share the same standard can communicate with each other regardless of device type or manufacturer. As a result, manufacturers have integrated the Modbus standard into their products for increased flexibility without paying royalties.
Modbus is divided into the following main types: Modbus RTU, Modbus ASCII, Modbus TCP/IP.
+ MODBUS-RTU
Modbus RTU works on the principle of Master – Slave, that is, one side receives the signal (Master) and one side transmits the signal (Slave) through register addresses. Modbus RTU uses a physical transmission method such as RS232/RS485. Modbus RTU is binary encoded with 1 data byte and 1 communication byte at a baud rate of 9600 – 57600.
+ MODBUS ASC II
Modbus ASC II is encoded in hexadecimal – 4 bits, requiring 2 bytes of communication for one byte of information. With Modbus display type, users can read packets directly without going through Master devices. So, Modbus ASCII cannot communicate with Modbus RTU and vice versa
+ MODBUS TCP/IP
Modbus TCP has the same operating principle as Modbus RTU, except that Modbus TCP uses a method of transmission over the internet or is also known as Modbus IP corresponding to an IP address. And this is and has become a trend that programmers love and use at present and in the future.
Konnex
KNX (Konnex) is an open standard (EN 50090, ISO / IEC 14543) for intelligent building automation and management systems; was developed on the basis of three previous standards: European Home Systems Protocol (EHS), BatiBUS, European Installation Bus (EIB). With the KNX standard, you can manage lighting, blinds, automatic doors, HVAC, security systems, energy management, video, audio, cameras and remote control…
Ethernet
Ethernet is a form of communication technology used to connect local LANs, allowing devices to communicate with each other through a protocol – a common set of network rules or language. As a data-link protocol layer in the TCP/IP layer, Ethernet shows how network devices can format and transmit data packets, so that other devices on the same local area network segment can detect, receive, and process such data packets. An Ethernet cable is a physical wiring to transmit data over.
Compared to wireless LAN technology, Ethernet is often less prone to interruptions whether due to radio interference, physical obstacles, or bandwidth. Ethernet also provides a better level of security and control over the network than wireless technology (devices must be connected by physical cables – outsiders will have difficulty accessing network data or trying to control the network). Bandwidth direction for devices is not provided.
Currently, the most commonly used Ethernet technology is that of 10-Mbps twisted-pair cables. 10-Mbps communication technology uses a large coaxial cable system, or double cable, fiber optic cable. The standard speed for Ethernet systems today is 100-Mbps, 1000-Mbps.
CAN (Control-Area-Network)
CAN is an acronym for Control Area Network, derived from a joint development of two companies Bosch and Intel to serve the networking in motor vehicles to replace the classic point-to-point connection. later internationally standardized in ISO 11898. With some large-sized automobiles, the total conductor length in point-to-point connections can be up to several kilometers, and conductor densities up to hundreds of kilograms. Only these two factors have shown the effectiveness of using a fieldbus system such as CAN (CANbus) to solve this problem. Thanks to the relatively high transmission speed at short distances and the advantages in some technical characteristics, this technology has been introduced into several fields of industrial automation.
CAN is a domain control network that allows devices in the bus to communicate with each other through only 2 wires (CAN-High and CAN-Low). Devices in the same Bus are called Nodes (in cars, they can be considered as ECUs), they can be up to several dozen Notes in the range from a few hundred meters to a few kilometers and still ensure the speed. signal transmission. That’s what sets CAN apart from other protocols.
Currently, in addition to CANbus, we also hear about other industrial communication protocol concepts such as: CANopen, CANlayer2, DeviceNet => they are all built on the CAN standard.
EtherCAT
EtherCAT (Ethernet for Control Automation Technology) was originally developed by Beckhoff Automation, a manufacturer of PLCs (Programmable Logic Controllers) used in real-time control systems and industrial automation.
They developed their own version of Fieldbus called “LightBus” in the late 1980s, to solve the bandwidth problem of other interfaces. Additional application on this protocol eventually led to the invention of EtherCAT.
Beckhoff introduced EtherCAT to the world in 2003. And then in 2004 they empowered ETG (EtherCAT Technology Group) who are responsible for promoting the standard. ETG has a very active developer and user group. EtherCAT is standardized according to IEC 61158 and is an industry communication standard.
So plctop.com has finished learning about some industrial communication protocols with you, hope you learn a lot from this article.
