CN201307236Y - Multi-channel serial communication converter and distributed control system employing same - Google Patents

Abstract

The utility model relates to a multi-channel serial communication converter, which extracts required data, status, etc. from information uploaded by various devices with different serial communication interfaces, serial communication protocols, and serial communication parameters. After processing and sorting, the commonly used standard serial communication protocol is used for data transmission with the upper computer. For this reason, the multi-channel serial communication converter includes: a plurality of first communication interfaces compatible with the lower computer, one compatible with the upper computer The second communication interface, multiple slave microcontrollers use the first serial communication protocol compatible with the serial communication protocol of the corresponding lower computer to carry out data communication with the lower computer through the first communication interface, and one master microcontroller uses the first serial communication protocol compatible with the upper computer The second serial communication protocol compatible with the standard serial communication protocol of the computer performs data communication with the host computer through the second communication interface, wherein the master microcontroller transmits data with each slave microcontroller through an internal data bus.

Description

Multi-channel Serial Communication Converter and Its Applied Distributed Control System

technical field

The utility model relates to a data transmission device in an industrial automation control system, in particular to a multi-channel serial communication converter and a distributed control system for its application.

Background technique

With the development of computer technology, the distributed control system based on industrial PC has been widely used in the field of industrial automation. Referring to Fig. 1, the distributed control system is basically a two-level master-slave structure from the perspective of the system architecture, that is, the upper computer 10 adopts an industrial PC, and runs various programs under the operating system (such as Windows98/2000/XP) of the PC. configuration software. The lower computer 30 is a variety of industrial measurement and control equipment (such as instruments, modules, programmable controllers, frequency converters, etc.), all of which are equipped with various serial communication interfaces (such as RS232, RS485, RS422), and have respective serial communication protocols. The upper computer 10 and the lower computer 30 are connected by a serial communication bus 20. According to the difference of the serial communication interface and the difference of the serial communication protocol, the lower computer equipment 30 should be divided into multiple groups and respectively connected to a certain serial number of the upper computer 10. On the serial communication interface, the host computer 10 may need to expand multiple serial communication interfaces like this. It may also happen that the serial communication protocol of a device is not supported by the configuration software of the upper computer (non-standard serial communication protocol), so it is necessary to use its serial communication protocol to obtain the support of the configuration software. The analog signal interface of other equipment is used to collect the analog signal output by the analog signal interface of the above equipment, convert it into a digital signal and then transmit it to the host computer. This may bring new problems, such as conversion errors, susceptibility to interference, and increased cost (due to the increase of analog signal input/output interfaces) and so on.

Taking Figure 1 as an example, devices A, B, C, D, and E refer to devices with different serial communication protocols, which are distinguished by different letters. The serial communication protocols of devices D1 and D2 in the figure are not within the range supported by the configuration software of the upper computer, so the analog signal interface of device E1 must be used to collect the analog signals output by devices D1 and D2, and then converted to digital signals transmitted to the host computer. The industrial PC of this system needs to be expanded to four serial interfaces and four communication buses on the one hand, and four serial communication protocols need to be configured in the configuration software, which brings about increased configuration cost and complicated structure.

Utility model content

The technical problem to be solved by the utility model is to provide a multi-channel serial communication converter, which is used as a data buffer conversion device between the upper and lower computers of the industrial automation control system, from various serial communication From the information uploaded by the interface, serial communication protocol, and serial communication parameter equipment, the required data, status, etc. are extracted, and after processing and sorting, the commonly used standard serial communication protocol is used for data transmission with the host computer.

The technical solution adopted by the utility model to solve the above-mentioned technical problems is to propose a multi-channel serial communication converter, which is used for protocol conversion between the upper computer and multiple lower computers of the distributed control system, wherein each lower computer Have a serial communication interface and at least one serial communication protocol, the upper computer has a serial communication interface, the configuration software running on the upper computer has at least one serial communication protocol, and the multi-channel serial communication converter includes:

A plurality of first communication interfaces are connected to a plurality of lower computers in one-to-one correspondence, wherein each first communication interface is compatible with the serial communication interface of the lower computer connected thereto;

The second communication interface is connected to the upper computer, and the second communication interface is compatible with the serial communication interface of the upper computer;

A plurality of slave microcontrollers are connected to each first communication interface in one-to-one correspondence, wherein each slave microcontroller uses a first serial communication protocol compatible with the serial communication protocol of the corresponding lower computer to perform data communication with the lower computer; and

The main microcontroller is connected to the second communication interface, and uses the second serial communication protocol compatible with the serial communication protocol in the upper computer configuration software to perform data communication with the upper computer, wherein the main microcontroller is via An internal data bus transfers data with each slave microcontroller.

In the above multi-channel serial communication converter, the first serial communication protocol of each slave microcontroller is compiled according to the serial communication protocol of the corresponding lower computer.

In the above multi-channel serial communication converter, the master microcontroller controls the direction of data transmission with each slave microcontroller via an internal control bus.

In the above multi-channel serial communication converter, the internal data bus is a parallel bus.

In the above multi-channel serial communication converter, each slave microcontroller has a different address number, and the master microcontroller transmits data with each slave microcontroller according to the address number and stores the data.

In the above-mentioned multi-channel serial communication converter, a plurality of first communication interfaces can be one of RS232, RS485, RS422 serial communication interfaces respectively, and the second communication interface can be one of RS232, RS485, RS422 serial communication interfaces .

On the other hand, the utility model proposes a distributed control system, including a host computer, a plurality of lower computers and at least one multi-channel serial communication converter, at least one multi-channel serial communication converter is connected between the upper computer and the Between multiple lower computers, it is used for protocol conversion, wherein each lower computer has a serial communication interface and at least one serial communication protocol, the upper computer has a serial communication interface, and the configuration software running on the upper computer has at least one Serial communication protocol, each multi-channel serial communication converter includes:

A plurality of first communication interfaces are connected to a plurality of lower computers in one-to-one correspondence, wherein each first communication interface is compatible with the serial communication interface of the lower computer connected thereto;

The second communication interface is connected to the upper computer, and the second communication interface is compatible with the serial communication interface of the upper computer;

A plurality of slave microcontrollers are connected to each first communication interface in one-to-one correspondence, wherein each slave microcontroller uses a first serial communication protocol compatible with the serial communication protocol of the corresponding lower computer to perform data communication with the lower computer; and

The main microcontroller is connected to the second communication interface, and uses the second serial communication protocol compatible with the serial communication protocol in the upper computer configuration software to perform data communication with the upper computer, wherein the main microcontroller is via An internal data bus transfers data with each slave microcontroller.

Because the utility model adopts a multi-channel serial communication converter, the data and states transmitted by each lower computer through different communication interfaces and communication protocols can be processed and sorted to be unified with the configuration software of the upper computer. The second serial communication protocol compatible with the serial communication protocol is transmitted to the host computer. In this way, the hardware architecture and software configuration of the system can be greatly simplified, and devices with non-standard serial communication protocols can also be integrated into the system.

Description of drawings

In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation of the utility model will be described in detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram of an existing distributed control system architecture.

Fig. 2 is a schematic diagram of the structure of a distributed control system using a multi-channel serial communication converter according to the present invention.

FIG. 3 is a structural diagram of a multi-channel serial communication converter according to an embodiment of the present invention.

Figure 4A is a flow chart of the main microcontroller program of the multi-channel serial communication converter.

Fig. 4B is a flowchart of the slave microcontroller program of the multi-channel serial communication converter.

Fig. 5 is a schematic diagram of a mobile expert system for recycling inorganic wastewater using a multi-channel serial communication converter according to the utility model.

Detailed ways

The utility model proposes a multi-channel serial communication converter in order to solve the problem that the industrial automation control system needs to be equipped with multiple serial communication interfaces and multiple serial communication protocols, which is used in the upper and lower computers of the industrial automation control system Acting as a data buffer conversion device, the conversion performed by the serial communication converter may include serial communication interface conversion and/or serial communication protocol conversion.

Fig. 2 shows a schematic diagram of the structure of a distributed control system using a multi-channel serial communication converter according to the present invention. Fig. 3 shows a structure diagram of a multi-channel serial communication converter according to an embodiment of the present invention. Referring to FIG. 2 and FIG. 3 , a distributed control system 100 includes a host computer 110 , multiple slave computers 130 and multiple multi-channel serial communication converters 120 . The upper computer 110 adopts industrial PC for example, and runs various configuration software under the operating system (such as Windows 98/2000/XP) environment of the PC. The lower computer 130 can be various industrial measurement and control equipment, including but not limited to instruments, modules, programmable controllers, frequency converters and the like. These devices are equipped with various serial communication interfaces, such as RS232, RS485, RS422, and have their own serial communication protocols.

The upper computer 110 is configured with one or more serial communication interfaces, and the configuration software running on the upper computer has one or more serial communication protocols. In the embodiment shown in Figure 2, the upper computer 110 can only be configured with one serial communication interface, and the configuration software it runs has only one serial communication protocol, which is referred to as a standard serial communication protocol here, which can be The commonly used Modbus RTU protocol.

A plurality of multi-channel serial communication converters 120 are connected between the host computer 110 and the plurality of lower computers 130, and each converter 120 can be connected to a plurality of lower computers. The converter can perform interface conversion required for communication between the lower computer and the upper computer, such as converting the RS232 interface to the RS485 interface supported by the upper computer. More importantly, the converter can also perform the protocol conversion required for the communication between the lower computer and the upper computer, such as converting the data format transmitted by other serial communication protocols (generally serial communication protocols that are not supported by the configuration software of the upper computer) It is the data format of the Modbus protocol supported by the upper computer configuration software. According to needs, the multi-channel serial communication converter 120 can only perform interface conversion, or only perform protocol conversion.

As shown in Figure 2, the four devices numbered A, B, C, D, and E have different serial communication protocols. Wherein, the device A has, for example, a serial communication protocol compatible with the serial communication protocol of the host computer configuration software, that is, the configuration software supports the serial communication protocol of the device A. The distributed control system 100 adopts three multi-channel serial communication converters 120, and the three groups of lower-level computer devices numbered B, C, and D respectively perform interface and/or protocol conversion through the three multi-channel serial communication converters 120, Use a serial communication protocol compatible with the serial communication protocol of the configuration software to communicate with the host computer 110 . Because multiple devices of the same serial communication protocol can share a serial interface (just have different addresses), as shown in Figure 2, the industrial PC of the distributed control system of the present utility model only needs one serial interface, and the assembly Only one standard serial communication protocol needs to be configured in the state software.

Referring to FIG. 3 , the multi-channel serial communication converter 120 adopts an N-channel input/one-output structure, that is, N channels of serial information are input to the converter 120 , and one channel of serial information is output to the host computer 110 . The N channels of serial information input can adopt different serial communication protocols, and the output serial information of one channel generally adopts commonly used standard serial communication protocols.

Specifically, each multi-channel serial communication converter includes multiple (such as N, N is a positive integer>1) first communication interfaces 121, multiple slave microcontrollers 122, bus drivers 123, and a master Microcontroller 124, second communication interface 125; an internal data bus 126 and an internal control bus 127. The first communication interface 121 is connected to a plurality of lower computers 130 (refer to FIG. 2 ) in one-to-one correspondence, wherein each first communication interface 121 is compatible with the communication interface of the lower computer 130 connected thereto. Wherein, the first communication interface 121 may choose to adopt different serial communication interfaces, such as RS232, RS485, and RS422. The parameters (such as word length, baud rate, stop bit, parity bit, etc.) of each first communication interface 121 may be set differently.

The multi-channel serial communication converter 120 adopts the architecture of "one master microcontroller + N slave microcontrollers". Wherein N slave microcontrollers 122 are connected to each first communication interface 121 in one-to-one correspondence, and each slave microcontroller 122 is configured with a first serial communication protocol compatible with the serial communication protocol of the lower computer 130, so as to A communication interface 121 performs data communication with the lower computer 130 . In one example, due to the diversity of the serial communication protocol of the lower computer 130, the program storage space for serial communication protocol programming can be reserved in the slave microcontroller 122, and then, according to the lower computer 130 to be connected, select Or prepare a compatible serial communication protocol.

The master and slave microcontrollers 124 and 122 are connected with each other through the bus driver 123 with an internal data bus 126 , and the master microcontroller 124 transmits data with each slave microcontroller 122 through the internal data bus 126 . In addition, the main microcontroller 124 controls the flow of the above-mentioned transmission data through the internal control bus 127 .

The second communication interface 125 is connected between the main microcontroller 124 and the serial communication interface of the host computer 110 , and the second communication interface 125 is compatible with the serial communication interface of the host computer 110 . For example, both the second communication interface 125 and the host computer 110 use RS485 interfaces. Of course, the second communication interface 125 and the host computer 110 can also choose other interfaces such as RS232 and RS422.

In addition, the main microcontroller 124 also has a second serial communication protocol compatible with the standard serial communication protocol of the configuration software of the host computer, so as to perform data communication with the host computer through the second communication interface 125 . For example, the second serial communication protocol is Modbus protocol.

The master microcontroller 124 of the multi-channel serial communication converter 120 is responsible for the control of data transmission with each slave microcontroller 122 , as well as the process of sorting and uploading all data. Each slave microcontroller 122 is responsible for the reception of input serial data information (output by each device) and the process of data extraction. Their working process is described below.

The data transmission between the master and slave microcontrollers is carried out in a pre-agreed manner. In one embodiment, the program flow of the main microcontroller is as shown in Figure 4A. After starting, detect whether the upper computer needs to obtain data (step 201), if the upper computer does not need to obtain data, then wait for whether the sampling period arrives (step 201) 202), after the sampling period arrives, according to the current slave microcontroller address numbering and protocol transmission data (step 203), until the end of transmission (step 204), then update the slave microcontroller address numbering and organize and save the data (step 205 ). On the other hand, if the host computer needs to obtain data, it extracts the data and transmits the data with the host computer according to the standard serial communication protocol (step 206), until the transmission ends (step 207).

Correspondingly, refer to shown in Figure 4B from the program flow of microcontroller, after starting, detect whether master microcontroller needs to obtain data (step 301), if master microcontroller does not need to obtain data, then wait for whether the sampling period arrives (step 301) 302), after the sampling period arrives, transmit data according to the communication protocol of the device (step 303), until the end of the transmission (step 304), and then organize and save the data (step 305). On the other hand, if the main micro-controller needs to acquire data, it transmits the current data sequentially (step 306) until the transmission ends (step 307).

Fig. 5 shows a schematic diagram of a mobile expert system for recycling inorganic wastewater using a multi-channel serial communication converter. In the distributed control system 400 of the "Mobile Expert System for Recycling Inorganic Wastewater", basically the same structure as that of the distributed control system shown in Figure 2 is used, so it will not be described in detail here. Only the differences of this embodiment will be described. In this embodiment, the upper computer 410 uses the MCGS configuration software of Kunlun Tongtai. The three programmable logic controllers (PLC) are RS485 serial interfaces, using the Modbus RTU serial communication protocol; all the PH (pH), ORP (oxidation-reduction potential), EC (conductivity) instruments as the lower computer 430 are RS232 serial interface, but MCGS configuration software does not support its serial communication protocol. Through three multi-channel serial communication converters 420, the measurement data of all instruments can be collected, arranged in an agreed sequence, and uploaded to the host computer 410 through the RS485 serial interface with the Modbus RTU serial communication protocol. The above devices using Modbus RTU serial communication protocol and RS485 serial interface (three PLCs, three converters) occupy a serial interface of the host computer. In addition, the two regulating controllers occupy another serial interface of the upper computer, using the AI instrument serial communication protocol supported by the MCGS configuration software.

In the multi-channel serial communication converter 120 structure of this example, the main microcontroller adopts the AT89C52 single-chip microcomputer; each slave microcontroller adopts the AT89C2051 single-chip microcomputer; the serial interface is MAX232 and MAX485; the bus driver is 74HC245.

Therefore, in the above-mentioned application example of "Mobile Expert System for Recycling Inorganic Wastewater", three multi-channel serial communication converters are used to collect and convert serial information of multi-channel smart meters, and the PH, ORP, and EC data are completed. transmission. The upper computer only needs to use a small amount of serial interfaces and serial communication protocols, and can communicate with incompatible devices.

Although the present utility model has been disclosed above with preferred embodiments, it is not intended to limit the present utility model. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model should be defined by the claims.

Claims (8)

1. A multi-channel serial communication converter, used for protocol conversion between a host computer and a plurality of lower computers of a distributed control system, wherein each lower computer has a serial communication interface and at least one serial communication protocol, The host computer has a serial communication interface and at least one standard serial communication protocol, and it is characterized in that the multi-channel serial communication converter includes: A plurality of first communication interfaces are connected to a plurality of lower computers in one-to-one correspondence, wherein each first communication interface is compatible with the serial communication interface of the lower computer connected thereto; The second communication interface is connected to the upper computer, and the second communication interface is compatible with the serial communication interface of the upper computer; A plurality of slave microcontrollers are connected to each first communication interface in one-to-one correspondence, wherein each slave microcontroller uses a first serial communication protocol compatible with the serial communication protocol of the corresponding lower computer to perform data communication with the lower computer; and The main microcontroller is connected to the second communication interface, and uses the second serial communication protocol compatible with the standard serial communication protocol of the upper computer to perform data communication with the upper computer, wherein the main microcontroller communicates with the upper computer through an internal data The bus transfers data with each slave microcontroller. 2. The multi-channel serial communication converter as claimed in claim 1, further comprising an internal control bus, and the master micro-controller controls the data between each slave micro-controller via the internal control bus. direction of transmission. 3. The multi-channel serial communication converter according to claim 1, wherein the internal data bus is a parallel bus. 4. The multi-channel serial communication converter as claimed in claim 1, characterized in that, said plurality of first communication interfaces are respectively one of RS232, RS485, RS422 serial communication interfaces, and said second communication interface The interface is one of RS232, RS485, RS422 serial communication interfaces. 5. A distributed control system, comprising a host computer, a plurality of lower computers and at least one multi-channel serial communication converter, the at least one multi-channel serial communication converter is connected to the upper computer and a plurality of lower computers Between, in order to carry out protocol conversion, wherein each lower computer has serial communication interface and at least one serial communication protocol, described upper computer has serial communication interface and at least one standard serial communication protocol, it is characterized in that each A multi-channel serial communication converter including: A plurality of first communication interfaces are connected to a plurality of lower computers in one-to-one correspondence, wherein each first communication interface is compatible with the serial communication interface of the lower computer connected thereto; The second communication interface is connected to the upper computer, and the second communication interface is compatible with the serial communication interface of the upper computer; A plurality of slave microcontrollers are connected to each first communication interface in one-to-one correspondence, wherein each slave microcontroller uses a first serial communication protocol compatible with the serial communication protocol of the corresponding lower computer to perform data communication with the lower computer; and The main microcontroller is connected to the second communication interface, and uses the second serial communication protocol compatible with the standard serial communication protocol of the upper computer to perform data communication with the upper computer, wherein the main microcontroller communicates with the upper computer through an internal data The bus transfers data with each slave microcontroller. 6. The distributed control system as claimed in claim 5, characterized in that, said plurality of first communication interfaces are respectively one of RS232, RS485, RS422 serial communication interfaces, and said second communication interface is RS232, One of RS485, RS422 serial communication interface. 7. The distributed control system as claimed in claim 5, wherein the multi-channel serial communication converter also includes an internal control bus, and the master microcontroller communicates with each slave micro-controller via the internal control bus. The direction of data transmission between devices.

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