KR100267825B1 - General-purpose control board with the can capability - Google Patents

Abstract

The present invention provides a general-purpose control board capable of simultaneously performing a universal control function and a CAN communication terminal function applicable to various control target devices. The communication board according to the present invention has a high computing power by adopting a 16-bit microprocessor with a built-in CAN controller, and controls and monitors a target device through digital input / output ports and analog input ports. At the same time, when data needs to be delivered to another remote device, it can communicate at speeds up to 1Mbps via the built-in CAN communication terminal. In addition, the built-in serial communication port not only provides an interface with a host computer during system development but also provides an interface with a central computer for overall system control. Therefore, the general-purpose control board according to the present invention allows a lower level target device or input / output devices and a computer having a control function to be connected to the same CAN communication line.

Description

GENERAL-PURPOSE CONTROL BOARD WITH THE CAN CAPABILITY}

The present invention relates to a controller that can build a distributed control system when it is difficult to build in the existing centralized method as the control system is enlarged, such as vehicle control or factory automation, and in particular, to control distributed target devices. The present invention relates to a general-purpose control board with a built-in CAN communication function that can be performed by integrating functions and functions of a communication terminal supporting data exchange between target devices.

As the control system becomes more complicated and intelligent, and the performance and price of semiconductor devices such as microprocessors are improved and the price is lowered, the demand for a distributed control system is gradually increased, and a need for a real-time network for control is emerging. CAN (Controller Area Network) is used as a communication network that supports communication of such a control real-time network. CAN was originally developed as an automotive network protocol in the 1980s. Its high performance and low cost have been designated by ISO as the serial communication protocol ISO11898 international standard, and is widely applied to other industries. In particular, CAN's high data processing speed, strong immunity to electrical disturbances, and the ability to detect and correct errors are known to be widely used in various industries such as automobiles, manufacturing, aviation, and railway.

The CAN communication protocol defines the information exchange method between communication terminals defined based on ISO's OSI reference model. Among the seven layers of OSI, the architecture of CAN is defined across the lower two physical layers and the data link control layer. CAN can uniquely assign an identifier indicating the bus access priority according to the message type. In this case, the lower the number of identifiers, the higher the priority. This identifier prevents messages from colliding. Through the arbitration method of "non-destructive-bitwise", the message of the highest priority among the collided messages can use the bus without any delay and real-time data. Suitable for the transmission of

However, the use of CAN with the above advantages in fields such as factory automation or monitoring systems is not yet common, and is partially introduced and used in semiconductor-related unit devices. The main reasons are as follows. First, communication-only devices with reliable reliability have not been supplied smoothly. Second, a communication board that functions as a CAN communication line and a terminal connected to it is manufactured separately, but is in charge of controlling the target device. In order to connect to the existing control board, I think it was necessary to have various interface channels that match the signal interface specification of the control board. In other words, it must be equipped with an interface channel that is completely different from the CAN communication terminal that meets the interface specifications provided by the control board, such as VME-BUS, PCI-BUS, ISA-BUS, or a dedicated private bus. Accordingly, in the conventional distributed control method, RS-422 serial communication of 1: 1 communication method is mainly used without using CAN of a multi-drop method.

The above problem may be regarded as a problem caused by a lack of a dedicated device and a lack of an interface circuit for connection with a control board.

Accordingly, an object of the present invention is to solve the problem of designing a separate interface circuit by embedding a multidrop CAN communication terminal function in a general-purpose control board that can be widely applied to various target devices. It is to enable the control and communication functions of a distributed system.

In order to achieve the above object, a general-purpose control board having a CAN communication terminal function according to the present invention includes a CPU that includes a controller area network (CAN) controller and manages control, communication, and arithmetic operations; A RAM for storing data necessary for performing control, communication, and arithmetic operations when executing a control program mounted on the CPU; A CAN driver circuit for driving data of the CAN specification supplied from the CPU to conform to a multidrop specification to exchange data between target devices or between the target device and a main computer; An analog input circuit having an input of a plurality of channels, for receiving an analog signal from a target device and supplying the analog signal to the CPU; A digital input circuit having a multi-channel input section for receiving a digital signal from a target device and supplying the digital signal to the CPU; A digital output circuit having an output of a plurality of channels, for transmitting the digital output from the CPU to a target device; And a serial communication port connected to a host computer or a central computer to download or upload a control program or to support conversion of communication data.

1 is an internal configuration of a general-purpose control board having a CAN communication terminal function according to the present invention.

2 is a block diagram showing an interface state between the control board and the target device of FIG. 1 according to the present invention;

3 is a block diagram of a distributed control system employing the control boards of FIG. 1 in accordance with the present invention.

4A is a circuit diagram of a connection between a CPU, a memory, peripheral components, and a serial port in FIG. 1;

4B is a circuit diagram of the analog input stage in FIG.

4C is a circuit diagram of the digital input stage in FIG.

4D is an LED driving circuit diagram.

4E is a CAN driver circuit diagram in FIG. 1;

4F is a circuit diagram of a power supply stage.

4G is a circuit diagram of the digital output stage in FIG.

4H is a circuit diagram of a network ID input unit in FIG. 1;

<Explanation of symbols for main parts of drawing>

100: universal control board

110: CPU

120: network ID input unit

130: CAN driver dedicated to CAN communication

140: CAN driver dedicated to serial communication

150: serial port

160: digital serial port

170: digital input port

180: analog input port

200: target device

300: host computer

400: CAN bus

500: central computer

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram showing the internal functional configuration of the 16-bit control board 100 having a CAN communication function. The CPU 110, which controls, communicates, and computes, employs an Intel 87C196CA microprocessor. The microprocessor is a 16-bit microprocessor with a high performance, built-in CAN controller in the 80196 series, which is used in many industries. The ROM area in which the control program is mounted among the memory areas uses the internal PROM area of the microprocessor. The RAM required for operation during program execution has an access time of 60 ns. IDT71256 with SRAM to enable fast access. The external input / output part has 8 channels of digital input 170 and 160 output, and 6 channels of analog input 180, respectively. The digital input 170 uses a PC817 optocoupler and a low pass filter that separate the ground. It enters the input / output port of the CPU 110. The digital output 160 exits the input / output port of the CPU 110 and passes through a data register to the relay driver. The relay driver drives the relay according to the data stored in the data stored in the register. The analog input is passed to the CPU 110 via a low pass filter, and this signal is converted into a digital signal by an A / D converter stored in the CPU and processed. The serial communication port 150 using the MAX233 sends and receives bidirectional data using RS-232C protocol. CAN communication is managed by a controller built in the CPU. As a driver that matches the electrical standard, one of the MAX485 (140) for serial communication and the PCA82C250 (130) for CAN communication can be selected and used. The PCA82C250 (130) must be used to faithfully use the CAN specification, but the MAX485 (140) can optionally be used even when an electrical connection is made using the RS-485 protocol. The switch portion 120 for the network ID serves to determine the ID, which is the address of the CAN communication, not only in software but also in hardware.

2 shows an external interface of a 16-bit control board 100 having a CAN communication function. The device to be controlled is connected to the digital input 170, the output 160, and the analog input terminal 180. The state of the target device is monitored through eight digital input units 170 and six analog input units 180. The eight digital output units 160 control the target device through the operation of the relay. When it is necessary to exchange data with another target device 200, the central computer 500, or the like, communication is performed through the CAN ports 130 and 140. The serial port 150 connects the host computer 300 and the control board 100, such as downloading and uploading a control program in the development stage, and after development, the control board as needed. The communication data conversion function is supported when the 100 is connected to the central computer 500 or the like.

Figure 3 shows the overall configuration of an embodiment when the control board of the present invention is applied to the control of the actual distributed system. As shown in FIG. 2, the target devices 200 to be controlled by the entire system are connected to the control board 100 through the digital input / output 170 and 160 and the analog input terminal 180. All control boards 100 are connected via one CAN bus 400 and one of the control boards 100 is connected via a central computer 500 and a serial port 150. The central computer 500 manages the entire system to deliver commands, monitor status, and coordinate work among the target devices 200.

4 is a detailed circuit diagram of the control board according to the present invention, and FIG. 4A shows a connection circuit between the CPU U1 and the memories U6 and U7, peripheral components, and the serial port U8. U2 is an oscillator for supplying a clock to the CPU, and U3 is a dedicated device for applying a reset signal when supplying power to the CPU. U4 and U5 are elements for stably holding address signals output from the CPU. In addition, an address decoder (not shown) provides control signals to various elements. Pushbuttons S1 and S2 are input means for inputting data into this controller or next-level computer when an operator requires it in the field, and software is provided with a low pass filter to prevent bouncing when entering.

4B is a circuit including a low pass filter for noise cancellation as an analog signal interface circuit. The diodes used are protection circuits to protect against overvoltage and reverse voltage.

4C shows the connection of digital input stage 170 including a low pass filter for noise cancellation and an optocoupler for ground isolation. Low pass filters are used to remove unexpected high frequency noise and to prevent bouncing in the case of key inputs. 4D shows a data register U9 and a pull-up resistor circuit for driving the LEDs ready to check the status of the control board.

4E illustrates a driver circuit for driving a CAN specification signal provided by a CPU to meet a multidrop specification. When several controllers are connected to one communication line, the ground level of each controller is different and the driver circuit is frequently broken during the interconnection. Therefore, the power supply ground of the controller and the CAN driver circuit are prevented. An optocoupler circuit (U10, U11) was designed to separate the ground of the circuit. In particular, since the maximum speed of CAN communication is 1 Mbps, an optocoupler operable at 10 MHz or more is used, and a power circuit is used by using a DC / DC converter (U16 in FIG. 4F) to supply a separate power source separate from the controller power supply. Was designed. Next, the circuit was designed using two types of driver elements to provide a signal standard that meets the communication specifications. U12 is a CAN communication device PCA82C250, which converts signals input and output from the microprocessor to CAN_H and CAN_L signals that are ISO11898 CAN specifications. It guarantees communication speeds of up to 1 Mbps. U13 converts CAN communication signals to the 485_H and 485_L signals, which are commonly used in traditional fieldbuses. However, because the device's delay time is relatively long, it can be used only up to 256 Kbps, but it has the advantage of using a conventional field bus medium. In particular, the pull-up resistor and pull-down resistor (R1) connected to U13 are required to maintain the default value when there is no communication data, for example 4.7 kV, and the series connection resistor (R2) of 47 kW, for example, is used for impedance matching between the controller drivers. Used. In addition, U12 and U13 are commonly provided with a resistor R3 of 120 kV for impedance matching and termination of the entire communication line. After establishing the communication line, jumpers (Jumper; JP5) is used in connection. In addition, jumpers JP1-JP4 are for selecting one of U12 (PCA82C250) and U13 (MAX485). In other words, jumper JP1 and JP3 are connected when PCA82C250 is used, and JP2 and JP4 are connected when MAX485 is used.

FIG. 4F shows three types of power supply circuits U14, U15, and U16 with the ground supplied to the control board 100 separated. These power supplies are each used as power supplies for digital input, digital output and CAN communication.

4G illustrates a configuration of the digital output stage 160 including a relay, wherein the digital output from the CPU 110 is input to the data register U18 of the digital output stage 160 and is relayed according to the data stored in the register. U19 drives the relay.

4H illustrates a DIP switch input 120 circuit that allows a user to define an ID of a network. When constructing a distributed control system, each communication terminal is assigned a unique address, and a DIP switch is installed so that a user can input this unique address. This DIP switch is for setting the CAN communication ID in hardware and its output is connected to the CPU's data bus. Meanwhile, a U19 device is provided to remove data interference with various input / output devices. Several types of input / output devices are connected to the data bus of the CPU such as RAM, digital input, and digital output, and U19 prevents multiple data from flowing to the data bus through these input / output devices. Only data is connected to the data bus, allowing the CPU to read the correct data.

Compared to the 1: 1 serial communication method of RS-422 method used in the existing distributed control system, the system is much simpler by constructing a multidrop communication network. In terms of communication speed, 1 Mbps at 9600 bps Is improved.

In addition, the usage of the multidrop method is the same as that of the field bus of the RS-485 method, but the communication line arbitration can be used in the RS-485 method so that only one communication terminal can use a communication medium at a time. Although the actual communication is performed at a lower speed than the communication speed of the communication medium, the proposed hardware is used to perform the communication line arbitration in hardware, eliminating the burden for the communication handshake. Data transfer is possible.

In addition, in the embodiment of the present invention as shown in Figure 3 it is possible to perform the role of the control and communication of the distributed system through a single control board 100. In this case, the program mounted on the control board 100 connected to the central computer 500 converts the command of the central computer 500 into a CAN protocol and controls the control board 100 of the target device 200 having the target ID. In addition, the control board 100 connected to the target device 200 performs the two functions of converting the monitoring data of the CAN protocol sent to the central computer 500.

On the other hand, the control board 100 connected to the target device 200 receives a command with the CAN protocol, decodes it, and generates a monitoring data with the CAN protocol and transmits a control process suitable for the command transmitted to each target device 200. The program to run is loaded. At this time, each control board 100 connected to the target device 200 may be assigned an ID for identification on the communication, the ID is a DIP switch mounted on the control board 100 in addition to the method specified on the mounted program It is possible to set it to 120 and make it recognize when the loaded program starts up. In this case, there is an effect that the entire program can be operated without any modification in the situation of determining or changing the ID. As a result, the central computer 500 may transmit commands and receive monitoring data as if the target devices 200 distributed in each unit are handled as if they are directly connected devices. That is, as described above, there is an effect that it is possible to efficiently and integrally manage the control and communication of the distributed control system through the control board 100 of the present invention.

Although the present invention has been described in detail by way of examples, the present invention is not limited thereto, and various changes or modifications may be made without departing from the spirit and scope of the present invention.

Claims (12)

CPU that has a controller area network (CAN) controller and manages control, communication and arithmetic operations, RAM for storing data necessary for performing control, communication and arithmetic operations when executing the control program mounted on the CPU; CAN driver circuit for driving data of the CAN specification supplied from the CPU to meet the multidrop specification and exchanging data between target devices or between the target device and the main computer; An analog input circuit having an input of multiple channels, for receiving an analog signal from a target device and supplying it to the CPU; A digital input circuit having an input section of a plurality of channels, for receiving an analog signal from a target device and supplying it to the CPU; A digital output circuit having an output section of a plurality of channels, for transmitting the digital output from the CPU to a target device; Serial communication port for connecting to host computer or central computer to download or upload control program or convert communication data Universal control board with CAN communication terminal function, including. The universal control board having a CAN communication terminal function according to claim 1, wherein the digital input circuit, the digital output circuit and the CAN driver circuit each have a power supply circuit. The universal control board of claim 1, further comprising an ID input unit for allowing a user to define an ID for identification on CAN communication of the control board. 4. The universal control board with a CAN communication terminal function according to claim 3, wherein the ID input unit is a DIP switch circuit. The CAN driver circuit of claim 1, wherein the CAN driver circuit includes a CAN communication dedicated device for converting a signal input and output from the CPU into a CAN communication signal and a serial communication device for converting a CAN communication signal into a serial communication signal. General purpose control board with communication terminal function. The CAN communication terminal function as claimed in claim 5, wherein a pull-up resistor and a pull-down resistor are connected to the serial communication element to maintain a default value when there is no communication data. One universal control board. 6. The CAN communication terminal function according to claim 5, wherein a resistor and a jumper are commonly connected to the CAN communication dedicated element and the serial communication element for impedance matching and termination of the entire communication line. Universal control board with. 6. The universal control board with a CAN communication terminal function according to claim 5, wherein the CAN driver circuit comprises switch means for separating the power ground of the control board and the ground of the CAN driver circuit. 9. The universal control board with a CAN communication terminal function according to claim 8, wherein said switch means is a pair of optocoupler circuits. The universal control board of claim 1, further comprising an LED driving circuit including data registers and pull-up resistors for driving the LEDs for checking the status of the control board. The universal control board of claim 1, further comprising a push button for inputting data into a control board or a next higher computer as needed by an operator when working in the field. Central computer, A plurality of control board according to any one of claims 1 to 10, and Target apparatus connected to each of the plurality of control boards Including; The control boards are interconnected via a CAN communication bus, wherein any one of the plurality of control boards and the central computer are interconnected via a serial communication bus.