KR0133202B1 - Network interface board system - Google Patents

Abstract

none.

Description

Network interface board

The present invention relates generally to an interface between a network of industrial programmable logic controllers and a general purpose processor, and more particularly to an interface board that provides an interface between a personal computer and a network of industrial programmable logic controllers.

Background of the Invention

A programmable logic controller or programmable controller is used to control the operation of punch presses, screw machines and automatic welders. Each programmable ligic controller, or PLC, receives information about the operation of the punch press or screw machine on the sensor and controls the operation of the punch press or screw machine through valves and switches. Thus, the PLC controls the operation of the punch press or screw machine to position the material in the working position, to work on the raw material, and to remove the finished product from the working position.

Several of these PLCs can be contacted with each other via communication lines to integrate component manufacturing throughout the entire plant. For example, from a central controller, the raw material may go through several different machines and processes in completing the manufacture of the article. Communication lines through which control and status information of several machines are transmitted continuously transmit data at baud rates ranging from 62.5K baud to 500K baud depending on the distance between the PLC and the central processor.

The order of occurrence of communication on the communication network is limited to the required proper order of source address, destination address, register read and write indicator, register address, and the number of registers to be read or written. In addition, the network communication defines when each PLC transmits and receives messages over the network communication line in a special way to avoid communication losses while having the ability to transmit the necessary information within a certain interval. All these communication definitions are commonly referred to as communication protocols.

Conventionally, a PLC is connected to a communication network via a simple interface circuit, and a software program in the PLC has a driving force following a communication network protocol for transmitting and receiving information. This requires the attention of many PLCs and consumes more time for the central processing unit to process the received information.

A network interface module that connects to a network via a PLC exists to coordinate protocols for transferring information between the PLC and the network. However, such a network interface module does not provide a feature that substantially simplifies the transfer of information between the PLC and the network interface module. Even if the PLC is connected to a network interface module, there is still a need for central processor software that performs redundant functions beyond normal control and throughput. For example, the network interface module delivers an alert message directly from the communication network to the PLC as if the alert message were instructions to write information to or read information from the desired register. The network interface module also passes an unsolicited message directly from the communication network to the PLC at a time that includes when the PLC is operating on the information required from the remote PLC. Furthermore, the network interface module provides a transmission lead to a central processor that is not standard for currently available personal computers, such as IBM PC compatible desktop devices.

Summary of the Invention

The present invention provides a network interface for providing expansion port signals and connectors for commercially available computers such as IBM PC compatible devices. The interface board (card) also simply programs a personal computer. The network interface board also provides a mail box of messages from the communication network and a queue of alert messages that the computer can access (access) in any order desired. An interface board using a direct memory address (DMA) device has an address location defined by asynchronous access to the personal computer described above.

An alert message is one of three types of messages identified as alert, fault and warning. With regard to automatic welding machines, an alarm message means that the electrode is out of the proper working position and is still in operation but the position must be changed. The fault message indicates that the SCR is destroyed so that no current flows through the electrode. The warning message indicates that the automatic welder is approaching a problem condition.

In combination with a message register, the network interface board provides an alarm queue including a dedicated portion of RAM memory sufficient to store each of the three types of twenty alarm messages. The microprocessor can access the alert message in the desired order and service the message in accordance with overall system operation.

Description of the preferred embodiment

1 shows a system including a monitor 13 and a computer in communication with a communication network 10 connected to control many industrial devices such as punch presses, welders and the like. The network interface board (hereinafter referred to as NIB) 21 of the present invention is mounted to an empty board or card slot in the computer 11 via an edge connector 29.

The network is a high speed industrial communication system. The network has a bus configuration with a single twinaxial cable that acts as a network communication path (see also FIGS. 1 and 3). Programmable controllers (PLCs) and other devices such as computers, printers, D-LOG modules, and CRT programmers are connected to the network through NIB 21 and network interface module (NIM) 31, which will be described in detail below.

The computer 11 with the NIB 21 monitors and supervises the programmable controller on the network. If it is recognized that a control action is required, the computer 11 can communicate the statement to the programmable controller. For example, the computer detects a shortage of material and instructs the remote programmable controller to start the conveyor to move the material from the alternate position.

Moreover, the system allows the personal computer 11 to quickly receive data generated in real time from a programmable controller. Such data may be parts count, machine operating time, temperature, statistical information and other programmable controller information. Once the generated data is received by the NIB 21, the computer prepares a management report and passes the data to another computer or initiates a real time control operation through a programmable controller.

The network interface board (NIB) 21 is installed in a long expansion slot of an IBM compatible personal computer. Since the NIB 21 is installed in the computer, the board 21 allows the computer to be connected to the network without the extra rack and power supply required when NIM is used.

The NIB 21 has four light emitting diodes (LEDs) that provide information about the operation of the board. The LEDs are designated networks, active, TX1 and RX1, and are located as shown in FIG.

The yellow network LED illuminates to indicate that it is operating on the network. Green LEDs indicate the operating status of the board. The yellow TX-1 LED flashes to indicate that the board is transmitting data to the device connected to the RS-422 port. The yellow RX-1 LED flashes to indicate that the board is receiving data from a device connected to the RS-422 port.

In addition to the RS-422 port and optical line 19, the NIB 21 includes an edge connector 29, which is a communication link between the NIB 21 and the computer 11. The computer 11 communicates with the NIB 21 via an edge connector to the board in parallel mode rather than through a serial RS-422 port.

The RS-422 port 22 allows, for example, a device other than the computer 11 to access the network via the board 21. These ports can be configured in different modes of operation.

The optical port 23 is used to connect the board 21 to the network 10. This is done via a network connector cable 24 that plugs into a port on the board and a Tee connector 41 on the network cable (see FIG. 5).

A DIP switch device with four switches 39 is mounted on the NIB 21. This switch is set to determine which address range in memory of the computer is assigned to the NIB 21 function.

In addition to the network interface, the NIB 21 supports programming software. With such software, the computer can be used to program and monitor the processor or data log module via direct cable connection or over a network as shown in FIG.

The application software 16 is on a disc that can be inserted into the disc driver 11A of the computer 11. It is of the type firmware (ROM or EPROM) plugged into the available software section NIB 21. The mailbox register 25 on the NIB 21 is described below.

The optical link 19 is located in the communication port 23 on the board 21 and on the communication line due to voltage surges that are reduced or amplified as a result of the operation of presses and welders connected to the communication network 10. It can increase the reliability of interference. The optical link 19 is connected via a suitable optical junction box 23 or the like.

The mailbox memory register 25 on the network interface card 21 is shown in FIG. The network interface board 21 provides a non-responsive message from the communication network to the mailbox 25, and provides an alert message in a queue format that the computer 11 can access in any order. The interface card 21 provides a direct memory access (DMA) device having an address location limited to asynchronous access by a personal computer and an interface card.

As shown in FIG. 2, the message control register of the mailbox 25 is used to set the byte count of the message block used for the command root, the remote address, and the read and write operations.

The write register buffer is used to store register data to be sent to the remote device. The response register is used to store input data received by the network interface board 21 in addition to the alarm message. The alert message buffer is used to store the input alert message. The alarm control device is used to control the observation, acknowledgment (ACK) and reset of alarm messages. Configuration and interrupt control devices are used to set parameters such as baud rate, network size and RS-422 port parameters.

Importantly, the NIB 21 has 34 each alarm queue. Three priorities, alarms, faults and warnings, are received from the programmable controller PLC and interpreted by the personal computer 11. The personal computer 11 may display an alert, affirmatively respond to the alert, store the alert information, or take supervisory action by the received alert.

An example of the operation of the mailbox register of FIG. 2 is as follows. Assume that an alert message has been received indicating that the welder electrode is moving out of the proper working position and that the position should be changed.

This message is received at network interface card 24 and mailbox 25 in the alert message buffer.

Of course, note that, as shown in FIG. 2, the setting of the network interface card 21 and the interrupt control register are initially set as appropriate network communication parameters as is known.

When a nonresponsive alert message is received, the alert control register controls the observation, acknowledgment and reset of the alert message. The computer responds positively to the alert message and sets an applicable acknowledgment register of the alert control action of the mailbox. If the alert message is positively acknowledged, the alert control register resets or deletes the specific message.

If it is necessary to send a message to various devices, for example, to send an alarm, the message is stored in a write register buffer. The message control buffer is then used to set the root, remote address, and number of bytes of the message block to be sent. The response register buffer is used to store all input messages to the NIB 21. An alert message is similar to a write message except that the alert message sends a constant value (alarm code) that is not variable data from the storage register. Resting devices can be programmed to respond to various alarm codes in a suitable manner.

As shown in FIG. 10, an area of memory for three alert queues is set. Each alarm queue can store 20 alarm messages in the order in which the alarm messages are received. Each stored alert message includes an alert code, a network route from the device sending the alert and optionally some additional alert data.

The three alarm queues are called warning doors, boundary doors and fault doors. With each of the three queues, the alert messages are classified at different levels. In general, warnings are the least serious alarms, economic doors are a bit more serious, and failure doors are the most serious alarms. However, the way each form is answered depends on how the user program is designed.

Each of the three alert queues has a register address, which causes the processor to send an alert message to the appropriate queue.

The message can be placed in an alert queue via an alert statement or a write statement. When a write statement is used, up to 5 data registers may be written to the alert queue as message locations. The first register acts as an alarm code, while the other four registers can provide additional data from the initiating device. The write rung allows more information to be sent to the queue than the alarm rung, and the data can be dynamically defined. That is, the alert code information can be loaded into a processor register that depends on real time I / O status and other real time status. As an alarm command, the alarm code is fixed when a ladder program is generated.

The user program uses the OP code to observe the alarm, acknowledge the alarm (with the sending device), and delete the alarm from the queue.

When an alert is received on an alert queue, the change flat for that queue is set to a new count.

Each alarm change has a flag position selected.

For example, the location is given by

Fault queue 2H

Alert queue 3H

Warning queue 4H

The user program can be designed to poll a flag change or be interrupted by a flag change. The program can then observe the error code and take other appropriate action.

To observe the alarm, the user program selects the alarm of the queue to be viewed and copies the alarm data into a buffer where it can be observed. The procedure to observe the alarm message is as follows.

Referring to Figure 10,

1. The user program detects an alarm change flag.

3. The user program checks the alarm count location for the appropriate queue to determine the number of alarm messages.

3: The user program selects the messages 1-20 in the queue to observe. This places the number in the alarm selection position.

4. The user program places the observation command OP code within the alarm command position.

5. The user program sets the GO flag 240H to a non-zero value.

6. When the GO flag is cleared, the selected message is used to observe, and the routine information for this message is available in the message root buffer.

If such an application requires it, the user program can positively respond to the alert (sent the alert code back to the calling device).

When a write rung is used to send a group of registers as an alert message, only the first register is written back to the originating processor in a positive response.

The procedure for acknowledging an alarm message is as follows.

1. The user program sets the number of alarm messages to be acknowledged in the fault queue, boundary queue, or warning queue.

2. The user program places a positive response command OP code within the designated alarm command position.

3. The user program places a value in the designated acknowledgment register that determines which register in the initiator to return the alarm code to.

4. Set the user program GP flag to a non-zero value.

5. The NIB 21 deletes the GO flag when the message has been acknowledged.

The alarm message remains in the alarm message until deleted by the user program. Once the alert queue is filled, the NIB 21 cannot accept any further alert messages for the queue.

Alert messages can be deleted individually (after they are usually observed) with delete statements. There is also a statement that deletes all three alert queues simultaneously.

1. The user program sets the number of alarm texts to be deleted in the alarm selection position.

2. The user program places the delete command OP code within the alarm command position.

3. The user program sets the GO flag to a non-zero value.

4. The board of NIB 21 deletes the GO flag when the message is deleted.

To delete all alarms, the following procedure can be used.

1. The user program places all alarm OP codes for deletion within the alarm command position.

2. The user program sets the GO flag to non-zero.

3. The NIB 21 deletes the GO flag when all alarm queues have been deleted.

Devices on the network can write data in the equivalent (mailbox) registers of the processors contained on the NIB 21. This allows the NIB 21 to receive nonresponsive data.

The register change flag position contains the address of the last register to be written. When a block of registers is written, the register change flag position contains the lowest register number of the block.

By monitoring the register change flag, the user program does not need to pull all 512 registers to detect the change statement. The board of NIB 21 may also be configured to generate an interrupt to the personal computer each time a mailbox register is written.

The register address in the register change flag is only deleted by the NIB 21 upon startup and restart. Repeated writes for the same mailbox register do not change the address in the register change flag after the first write.

However, each write to the mailbox register generates an interrupt to the computer 11 if this interrupt condition is met.

The NIM 31 manages network communications to mitigate the user program of this task. As will be explained, the NIM 31 may flag a user program when a response, alert condition or non-responsive message is received. Referring to FIG. 3, an additional RS-422 port 22 is provided in each NIM 31, which allows the second device to access the network via the NIM. That is, each NIM 31 supports two devices. Note that only NIM 31 is connected to the network. The PLC and the device (see FIG. 1) are connected to the network line 24 via the NIM 31.

1, 7, and 9, NIM 31 allows two devices (programmable controller, CRT programmer, computer, printer, etc.) to connect to the network. Since up to 100 network interface modules NIM 31 may be connected to a single network, and each NIM 31 may connect two devices to the network, the network may have a maximum of 200 devices. However, more devices can communicate by connecting multiple networks together, as shown in FIG.

The network interface module NIM 31 is installed in a thyristor slot of a programmable controller I / O rack assembly. The IM 31 has a two digit thumbwheel that sets the number of network addresses between 00 and 99.

This number of addresses identifies the NIM module and the devices connected to it, and also sets the communication priority that the NIM module has with respect to other NIMs on the network.

The NIM has two RS-422 COMM ports to which a programmable controller or other device is connected. This port number is combined with the NIM address number to identify the device for network communication.

1 is a block diagram showing the connection of a network board between a personal computer and a communication network.

2 is a schematic block diagram of a register provided on a network interface card for transferring information between a microprocessor and a communication network.

3 is a schematic block diagram of commercially available components and the interconnection of the components affecting the interface card of the present invention.

4 is a perspective view of a network interface card of the present invention.

5 shows a connection from a network interface card to a network cable.

6 is another illustration of a network interface card showing output ports and terminal connections.

7 is a perspective view of the network interface module 31 (see FIG. 1).

8 is a diagram of a register of the network interface module of FIG.

9 is a diagram illustrating a method of interconnecting two networks through two network interface modules.

10 shows three information queues.

Related application materials

This application is filed simultaneously with the present application, and is named Network Communication System (List No. 401p044); Ladder sequence controller (list 401p045); Peer-to-peer register exchange controller for PLC (List No. 401P046); And an application which is a restraint press control system (List No. 401P047). The contents of these applications are incorporated herein by reference.

Claims (10)

A network interface board for facilitating communication between a plurality of programmable logic controllers connected to a communication network arranged in a bus structure for controlling personal computers and machines having a memory space, comprising: (a) the network interface board 21; Terminal means 29 for connecting a computer to the personal computer, (b) port means 23 for connecting the network interface board to the communication network, and (c) the port means and the terminal means. Mailbox memory means 25 for reading and writing messages by the personal through the terminal means and by the programmable logic controller through the port means, and (d) a message received from the programmable logic controller; Store the received messages Response register means for sending to a null computer, (e) a write register in said mailbox memory means for storing and sending messages from said personal computer, and (f) messages stored in said write register means. Control register means for setting addresses and routes of the programmable logic controller for selectively sending to the programmable logic controller, (g) storing an alert message received from the programmable logic controller, and storing the alert message Alarm register means in the mailbox memory for sending to the personal computer, and (h) address mapping means for mapping the response register means, the write register means, and the alarm register means into a memory space of the personal computer. The personal computer directly accesses the response register means, the write register means, and the alert register means in a predetermined sequence, wherein the alert messages include a fault message, a warning message, a warning message, and the alert register means And an alert queue, prioritized, wherein the queue includes the address mapping means for storing the fault message, the alert message, and the alert message. The network interface board of claim 1, wherein the terminal means comprises an edge connector for inserting into an expansion card slot of the personal computer to provide a parallel connection to the personal computer. The network interface board of claim 1, wherein the personal computer directly accesses the alert queue in a predetermined sequence. 2. The network interface board according to claim 1, wherein said port means is optically separated for connecting to said communication network. 2. The personal computer of claim 1, wherein the personal computer directly programs the one programmable logic controller by storing a program step message in the write register means and sending the program step message to the one programmable logic controller. Network interface board. The network interface board of claim 1, wherein the network interface board includes an input / output serial RS-422 port for connecting to an intelligent device by direct cable connection. 6. The network interface board of claim 5 wherein the intelligent device is a programmable logic controller. 6. The network interface board of claim 5, wherein the intelligent device is a personal computer. The network interface board of claim 5, wherein the intelligent device is a printer. 6. The network interface board of claim 5 wherein the intelligent device is a CRT programmer.

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