Three major industrial bus networks - — 485 network, HART network, fieldbus networks - — The present situation of

The current industrial bus network can be classified into three categories: 485, HART network, FieldBus field bus network. 485 network: RS485 / MODBUS is popular now a way of industrial network, its characteristic is simple and convenient implementation, and now supports RS485 instrument is much more special. Now instrument traders have also in favour of RS485 / MODBUS, for the simple reason that transformation of RS485 interface not only cheaper but also are varied. At least in the low-end market, RS485 / MODBUS will still be the main way of industrial network. HART network: HART is an excessive sexual bus standard proposed by Emerson, main characteristic is in 4 - Stacking up 20 ma current signal digital signal, but the deal has not really open, to join his foundation to get agreement, and in a foundation to a fee. HART technology mainly dominated by several large companies abroad, in domestic in recent years, companies have to do it, but have not reached the level of foreign companies. Now there are a lot of intelligent instrument with [ HART round card] With the HART communication function. But there is no real from domestic situation, use this part of the function for network monitoring equipment, just use hand most operator to set parameters. In the long run, due to difficulty of HART communication rate is low, the networking, the application of the HART instrument will be a downward trend. FieldBus profibus network, field bus is one of the hotspot in the field of automation technology, known as the computer local area network (LAN) in the field of automation. It marks the automation control technology and the beginning of a new era. Fieldbus is the scene of the connection control digital instrument and control indoor control device, serial, multistation communication network. The key logo is to be able to support two-way, multi-node, bus type of all digital communication. Fieldbus technology in recent years become the hotspot in international automation and instrumentation development, it makes the traditional control system structure produced revolutionary change, make the automatic control system in the 'intellectualization, digitalization, informatization and networking, diversified' in the direction of further and form a new type of network communication of total distributed control system -- — FCS (fieldbus control system 现场总线控制系统) 。 So far, however, the field bus has not form a truly unified standard, ProfiBus, CANbus, CC - Link such as a variety of standard parallel exists, and both have their own living space. When is unified, remote. At present, the support fieldbus instrument category is less, alternative room is small, the price is on the high side, dosage is small.