Discussion on Compatibility of Industrial Sensors and Communication Protocols
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At present, there are many manufacturers of industrial computer, PLC, and bus products on the market. There are many kinds of bus protocols. The main fields of factory automation are: Ethernet, CANopen, DeviceNet, PROFINET, PROFIBUS-DP, PROFIBUS-FMS, etc.; the main fields of process automation are: : FoundationFieldbus (FF), PROFIBUS-PA, P-NET (ProcessautomationNet), etc.; and each protocol is independent and incompatible with each other, which brings a lot of inconvenience to the customer’s application, which is very important for the customer-oriented market situation. It is undoubtedly not conducive to the long-term and stable development of the industrial control industry. In this context, a revolution of industrial fieldbus technology is imperative. How to realize multi-network and multi-protocol interconnection and barrier-free operation is undoubtedly the development direction of industrial fieldbus technology.
The Ethernet network is undoubtedly popular, and the open Ethernet is the most successful network technology developed in more than 20 years, and has led to a revolution in information technology. With the development of network technology and the efforts of major network companies and automation companies (such as Siemens), it is foreseeable that Ethernet/IP will enter the industrial control system very quickly just like when PC entered the field of industrial automation. network at all levels.
At present, the industrial field bus is gradually turning to the Ethernet network, and the wide application of PROFINET is one of its manifestations. As a strategic technological innovation, PROFINET provides a complete network solution for the field of automation communication, including such as Real-time Ethernet, motion control, distributed automation, fail-safe and network security hot topics in the field of automation, and, as a cross-vendor technology, fully compatible with Industrial Ethernet and existing fieldbus (such as PROFIBUS) technology , protect the customer’s existing investment. But PROFINET is only a small step in the technological revolution, and there is still a long way to go in the future.
The above is the situation of the field bus protocol. Turning to the sensor, well-known sensor manufacturers in various automation fields have the technical strength to produce and manufacture sensor products that support the bus protocol. However, how to achieve compatibility with various existing bus communication technologies to the greatest extent is a difficult problem that manufacturers have to face, and it is also the direction of sensor technology development in the future. In order to better set parameters and store configuration data for control and indication, many sensors and actuators have been equipped with microprocessor systems, and have achieved point-to-point access to the control layer through communication technologies such as HART, IO-Link, etc. .
Therefore, I think that for various sensor suppliers, it is not only necessary to manufacture products that directly support general industrial fieldbus protocols, such as: rotary encoders that support CANopen, PROFIBUS-DP, DeviceNet protocols, linear displacement sensors and pressure, temperature, flow It is necessary to continuously develop and manufacture products that support point-to-point protocols such as HART and IO-Link. Such products not only have independent communication technology, but also can be compatible with the mainstream general network architecture. Meet the needs of sensor standardization and commercialization.
For the selection of sensor support protocols, versatility and practicability are the most important. Now the amount of information between sensors has exceeded that of computers or other applications, and has become the mainstream of information interaction. Interconnection with things.
Therefore, the technology of the sensor core chip and the sensor network connecting to the Internet will become the priority bottleneck in the progress of IT frontier technology in the next few years. In this way, how to better integrate the sensor with Zigbee communication technology,RFIDThe combination of communication technology, WI-FI communication technology, and 2G and 3G communication technology has become the main direction of future sensor development.
On the premise that the existing production and R&D technology can be satisfied, it is necessary to manufacture sensor/actuator products that support the mainstream industrial fieldbus communication protocol on the market as much as possible, so as to continuously adapt to the increasingly diverse market needs and better meet the needs of the increasingly diverse market. It has a place in the fierce market competition, so as to improve its own product competitiveness and better meet the needs of customers at different levels and industries.
In recent years, major sensor manufacturers have been pursuing the improvement of sensor functions and intelligence, in order to promote the continuous development of the automation field. But the interface is always the same, there is no major breakthrough. In order to achieve the unity and transparency of the interface at the field device layer, in 2004, major mainstream sensor manufacturers cooperated to establish a new association, focusing on the development and promotion of IO-Link interface technology, and Pepperl+Fuchs is one of the main members. Until 2011, with the introduction of various IO-Link interface sensors from Pepperl+Fuchs to the Chinese market, the IO-Link interface technology did not enter the Chinese market in the true sense.
In the current factory automation network, our most common sensors are only field devices for discrete signals (such as NPN, PNP digital signals) and continuous signals (such as current, voltage analog signals). Transparent data interaction also only stays at the control layer, between the programmable controller and the programmable controller, and between the programmable controller and the host computer. When the IO-Link interface technology is introduced, the sensor provides process data (discrete signal and continuous signal), and also increases the interactive function of maintenance data.
IO-Link interface technology is a new generation of point-to-point communication technology. Its advantages lie in unified access modules, unified installation wiring, unified software settings, unified data structure, maintenance-free plug and play, and the retention of standard I. /O interface. Specifically, unified access module: when the user selects the input/output module of the programmable controller, he does not need to consider the NPN or PNP module, the switch quantity or the analog quantity module, the 3-wire or 4-wire module; the programmable controller terminal Use the unified IO-Link master module. Unified installation and wiring: When designing, users do not need to consider the design of 2-wire, 3-wire, 4-wire or even 12-wire, and do not need to consider the choice of pin size, wire color and shielded wire; the sensor end is a unified three-wire design (power positive , negative power supply, IO-Link signal line). Unified software setting: Through the unified device parameter management text (IODDS), the data exchange and parameter setting between the sensor and the programmable controller can be easily realized. The user can set parameters and monitor the sensor by using the general-purpose IODDS text or the user-friendly IODDS text customized by the sensor manufacturer. Maintenance-free plug-and-play: In the traditional interface method, users need to reset the sensor according to the on-site situation when replacing spare parts. The user of the sensor with built-in IO-Link interface only needs to import the setting file saved in the past into the sensor. .
The next-generation IO-Link interface technology can also realize the automatic download of parameters after the sensor is connected, without user operation. Retain the standard I/O interface: Considering the replaceability of the current network, when designing the IO-Link interface, the input port of the IO-Link master module on the programmable controller side can be customized, which can be connected to conventional sensors or Connect to IO-Link sensor; the interface of the same IO-Link sensor can also be customized, which can be used as a conventional NPN/PNP sensor or as an IO-Link sensor, ensuring compatibility with current networks and devices. We have reason to believe that in the near future, IO-LINK interface technology is bound to become the leader of the field device layer interface technology in the entire sensor industry.
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