KR20000009541A - Serial communication device and method thereof - Google Patents

Abstract

PURPOSE: A serial communication device performs a communication between a master and a node by using one communication channel in 1:1 communication system. CONSTITUTION: In a serial communication device, one master(1) performs a polling of 1:N with many nodes(2,3,4), and performs a serial communication. One communication line(5) connects the master(1) to the nodes(2,3,4). CPU is connected to a communication element through address buffer, data buffer and a control bus. A control bus is connected to a receiving port. A transmission terminal of the communication element is connected to a transmission port. A receiving terminal is connected to a receiving port. An output terminal of the receiving port is connected to an output terminal of the transmission port, thereby reducing a cost, and facilitating a wiring of a communication line.

Description

Serial communication device and method

The present invention relates to a serial communication apparatus and method, and more particularly, to a serial communication apparatus and method for enabling communication between a master and a node using only one communication channel in a single N communication system in which one master polls multiple nodes. will be.

In general, in a 1N communication system in which one master polls multiple nodes, there are two communication channels between the master and each node so that the master uses channel 1 to transmit data to the node, and the node sends data to the master. When transmitting, using channel 2, the master transmits data while sequentially calling nodes one by one, and the called node transmits data to the master.

In this case, since the master does not transmit data from the node to the master at the moment of transmitting data to the node, it is not necessary to have two communication channels.

In this case, when one channel is used, the transmission port and the reception port share one channel, so when transmitting, it is possible to prevent the data transmitted by the user from returning to the user by disabling the reception function. By enabling the reception function again to receive, communication between the master and the node is possible using one channel.

1 is a block diagram showing a conventional serial communication apparatus, in which one master 1 and a plurality of nodes 2, 3, and 4 are connected via two communication channels 5 and 6, respectively. Configured to be connected at 1: N.

FIG. 2 is a block diagram showing the configuration of a communication device provided by the master 1 and the plurality of nodes 2, 3, and 4, respectively. As shown in FIG. It is connected to the communication element 25 through the data bus 23 and the control bus 24, the transmission terminal TX of the communication element 25 is connected to the transmission port 26, the communication element 25 The receiving terminal (RX) of is configured to be connected to the receiving port (27).

3 is a circuit diagram showing the configuration of the transmission port 26. As shown therein, the transmission terminal TX of the communication element 25 is connected to the input terminal 32 of the signal drive element 31 and the signal thereof. Drive element 31 is composed of two output terminals (33, 34), a circuit diagram showing the configuration of the receiving port 27 as shown in Figure 4, as shown in the input terminal of the signal receiving element 41 ( 42 and 43 are connected to the output terminals 33 and 34 of the signal drive element 31 of the transmission port 26, and the output terminal 44 of the signal receiving element 41 is received by the communication element 25. The operation of the conventional apparatus configured to be connected to the terminal RX and configured as described above will be described.

First, the master 1 communicates while polling each node 2, 3, and 4, wherein the signal transmitted by the master 1 is transmitted from the transmission terminal TX of the communication element 25 of the communication apparatus. (26), the signal input to the transmission port 26 is loaded on the communication lines (5, 6) via the signal drive element (31).

If the signal is transmitted to the nodes 2, 3, and 4 through the first channel 5 of the master 1, the signal is received by the signal receiving element 41 of the receiving port 27 of each node 2, 3, and 4. By this, the signal receiving element 41 of the receiving port 27 compares the level of the input signal and outputs a high potential if the difference in the signal level is positive, whereas the difference in the signal level Negative outputs low potential.

The signal output from the signal receiving element 41 is input to and processed by the CPI 21 of each node 2, 3, 4 through the receiving terminal RX of the communication element 25.

At this time, the CPI 21 of each of the nodes 2, 3, and 4 analyzes the received signal to determine whether it is a signal to respond to, and if it is a signal to respond, sends a corresponding signal to the master 1. Operate as above and transmit.

9 is a communication frame transmitted by the master 1 to each of the nodes 2, 3, and 4, and as shown therein, information of the nodes 2, 3, 4 and nodes 2, 3, 4) contains the contents to be processed so that only the corresponding nodes (2, 3, 4) will respond to the master (1), and FIG. 10 shows that the nodes (2, 3, 4) transmit data to the master (1). Is the structure of the communication frame.

However, in the communication system in which one master polls a plurality of nodes as described above, two channels exist between the master and each node, but two channels cannot be loaded at the same time. There is no need to provide a separate, and if two channels are provided separately, it is necessary to separate the transmission and reception channels when connecting the communication line, so there is a problem that a connection error may occur.

Accordingly, an object of the present invention is to provide a serial communication apparatus and method for communicating using a single communication channel between a master and each node.

1 is a block diagram showing a configuration of a conventional serial communication device.

Fig. 2 is a block diagram showing the construction of a communication device in Fig. 1;

3 is a circuit diagram showing the configuration of a transmission port in FIG.

4 is a circuit diagram showing the configuration of a receiving port in FIG.

Figure 5 is a block diagram showing the configuration of the serial communication device of the present invention.

Fig. 6 is a block diagram showing the construction of the communication device of the master in Fig. 5;

Fig. 7 is a block diagram showing the construction of the communication device of the node in Fig. 5;

8 is a circuit diagram showing the configuration of a receiving port in FIG.

9 shows a state of a frame transmitted from a master to a node.

10 is a view showing a frame transmitted from a node to a master.

FIG. 11 is a flowchart of an initialization operation of a master in FIG. 5; FIG.

Fig. 12 is a flowchart of operation of the master in Fig. 5;

Fig. 13 is a flowchart of operation of the node in Fig. 5;

***** Description of the symbols for the main parts of the drawings *****

1: master 2, 3, 4: node

5,6: Communication channel 21,61,71: CPI

22,62,72: Address bus 23,63,73: Data bus

24, 64, 74: Control bus 25, 66, 76: Communication element

26,67,77: sending port 27,68,78: receiving port

31, 81: signal drive element 41, 91: signal receiving element

79: input port 80: output port

In order to achieve the above object, the present invention provides a serial communication device in which one master having a communication device is in serial communication while polling at 1: N with a plurality of nodes having a communication device. It is characterized by being connected by one communication line.

The present invention for achieving the above object comprises a first step of initializing the master; A second process of the master processing the data received from the node as an interrupt and transmitting and receiving data through one communication channel; When a node receives data from the master, an interrupt is generated to perform a third process of transmitting and receiving data with the master through one communication channel.

Hereinafter, operations and effects of the serial communication apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

5 is a block diagram showing the configuration of the serial communication apparatus of the present invention. As shown in the drawing, the general configuration is the same as in the related art, except that the master 1 and the plurality of nodes 2, 3, and 4 are connected to one communication line ( 5) to connect.

Fig. 6 is a block diagram showing the configuration of the communication device of the master 1 of the present invention. As shown in this figure, the CPI 61 passes through the address buffer 62, the data bus 63, and the control bus 64. It is connected to the communication element 66, the control bus 64 of the CPI 61 is connected to the receiving port 68, the transmission terminal TX of the communication element 66 is connected to the transmission port 67 The receiving terminal RX of the communication device 66 is connected to the receiving port 68 and is configured by connecting the output terminal of the receiving port 68 and the output terminal of the transmitting port 67.

FIG. 7 is a block diagram showing the communication device of the nodes 2, 3, and 4 of the present invention. As shown in FIG. 7, the communication device of the master 1 is the same, except that The configuration differs by connecting the input port 79 and the output port 80.

8 is a circuit diagram showing the configuration of the reception port 68 of the present invention. As shown in FIG. 8, the output terminal of the transmission port 67 and the input terminals 92 and 93 of the first signal receiving element 41 are connected to each other. And the output terminal of the second signal receiving element 94 connected to the input bus 64 of the CPI 61 and the input terminal is connected to the control terminal of the first signal receiving element 91.

Fig. 11 is an operation flowchart of the initialization of the master 1, and the first step S1 of designating the number of all nodes 2, 3, and 4 as shown therein; A second step S2 of initializing a flag for the communication state of each node 2, 3, 4 to '0'; A third step S3 of setting the addresses of the nodes 2, 3 and 4 to be called as the first node 2, 3 and 4; A fourth step S4 of setting the number of the communication error nodes 2, 3, 4 to the first node 2, 3, 4; A fifth step S5 of setting nodes 2, 3, and 4 in which the current polling mode is the communication normal; A sixth step S6 of calling the first node 2, 3, 4; A seventh step S7 of setting a time for waiting for a response from the nodes 2, 3, and 4; The eighth step S8 of setting the time taken to call all the nodes 2, 3, and 4 is performed.

Fig. 12 is an operation flowchart for the master 1, which determines whether a communication error interrupt has occurred (S21) as shown therein; Setting a communication state flag of a corresponding node (2, 3, 4) if a communication error interrupt has not occurred in step (S21); Storing the input port 79 data received at the nodes 2, 3, and 4 (S23); Determining whether a current mode is a polling mode (S24) when a communication error interrupt occurs in the step (S21); Clearing the communication flag of the corresponding device (S25) if the current polling mode is not present in the step (S24); Setting addresses (S26) of nodes (2, 3, 4) to be called next among nodes (2, 3, 4) in which communication is normal; Determining whether the call of the nodes (2, 3, 4) in which communication is normal is completed (S27); Calling (2,3,4) the node (2,3,4) selected in step (S26) if the call of the node (2,3,4) in which communication is normal is not completed; Setting the nodes 2, 3, and 4 in which communication is normal to a mode of calling (S29); Setting a waiting time for a response from the nodes 2, 3, and 4 and ending (S30); Setting the communication error mode to a mode in which the call of the nodes (2, 3, 4) in which communication is normal is completed (S31); Setting nodes (2, 3, 4) to be called among communication error nodes (2, 3, 4) in the current polling mode in step (S24); Determining whether or not the call of the communication error node (2, 3, 4) is completed (S33); Calling (S34) the communication error node (2,3,4) selected in step (S33) if the call of the communication error node (2,3,4) is not completed in step (S33); If the call of the communication error node (2, 3, 4) is completed in step S33, calling the node (2, 3, 4) with a value greater than the address of the last node (2, 3, 4) ( S35); Initializing an address to be called among the communication error nodes 2, 3, and 4 to '0' (S36); Determining whether the time period for calling all the nodes (2, 3, 4) has elapsed (S37); If the time taken to call all nodes 2, 3 and 4 has not elapsed in step S37, the time taken to return to step S30 and calls all nodes 2, 3 and 4 has elapsed. Setting the number of nodes (2, 3, 4) to be called currently as the first node (2, 3, 4) (S38); After setting the time taken to call all nodes 2, 3, and 4, the process returns to the above step (S39).

Fig. 13 is a flowchart of operations for nodes 2, 3, and 4, as shown therein, in which step S51 of reading data transmitted from the master 1; Determining whether the address of the receiving station and its address match (S52); In step S52, if the receiving station address and its address do not match, the process is terminated. If the receiving station address and its address match, outputs managed by the nodes 2, 3, and 4 are transmitted from the master 1; Outputting to the port 80 (S53); In step S54, the state of the input port 79 managed by the nodes 2, 3, and 4 is transmitted to the master 1 and then terminated.

Such operation of the present invention will be described in detail.

First, when the master 1 transmits data to the nodes 2, 3, and 4, the control signal of the CPI 61 is output at low potential to disable the function of the reception port 68 of the communication device. The data to be transmitted is transmitted to the transmission port 67 through the transmission terminal TX of the communication element 66, whereby the signal drive element 81 of the transmission port 67 has the same signal and inversion as the input signal. Outputs a signal, which is transmitted to each node (2, 3, 4) via a single communication line (5).

After that, when the transfer of the data to the nodes 2, 3, and 4 is completed, the master 1 functions to receive the signal from the nodes 2, 3, and 4 with the high potential of the control signal. Enable

The signal transmitted from the master 1 is input to the signal receiving element 91 of the receiving port 78 of each node 2, 3, 4, and accordingly the signal receiving element 91 of the receiving port 78 Compares the level of the input signal and outputs a high potential if the difference in the signal level is positive, and a low potential if the difference in the signal level is negative, the output signal through the receiving terminal (RX) of the communication device 76 71 is transmitted and signal processed.

That is, the data transmitted from the master 1 is transmitted to the receiving port 78 of each node 2, 3, 4 through a single communication channel 5, which is received at each node 2, 3, 4 The signal is analyzed to determine whether it is a signal to which it has responded.

Here, the communication frame transmitted by the master 1 to each of the nodes 2, 3, and 4 is recorded in the frame by inserting information of the nodes 2, 3, and 4 to receive the signal as shown in FIG. Only nodes (2, 3, 4) having the same address as the station address transmit data to the master (1).

At this time, the master 1 reads the state of the input port 79 of each node 2, 3, 4 by serial communication with each node 2, 3, 4, Outputs data to the output port 80, and when the master 1 polls the nodes 2, 3 and 4 sequentially, all nodes 2 and 3 according to the number of nodes 2, 3 and 4 The time to poll, 4) varies, i.e. if it takes t msec to call one node (2,3,4) and the node (2,3,4) responds, then the entire node (2,3) When N, 4) is N, the time taken to poll all nodes 2, 3, and 4 becomes t * N msec.

Here, in the case of the nodes (2, 3, 4), the time to be called from the master (1) is variable according to the number of nodes (2, 3, 4), in particular the number of nodes (2, 3, 4) In this case, the nodes 2, 3, and 4 have a short time to be called from the master 1, so the present invention keeps the time of calling the nodes 2, 3, and 4 from the master 1 constant. That is, the master 1 starts the timer when calling the first node (2,3,4) and checks whether the timer has elapsed when the last node (2,3,4) is called. After this elapses, the first node (2, 3, 4) is called again.

Then, the master 1 manages the communication state of each node (2, 3, 4) to preferentially call the nodes (2, 3, 4) communication is normal, the nodes (2, 3, 4) communication is normal When the call is completed, the node (2, 3, 4) having a communication error is called.

Here, the initializing operation of the master 1 will be described. First, the number of get of all the nodes 2, 3, 4 is specified, and the communication state flag of each of the nodes 2, 3, 4 is set to '0'. Initialize

After that, the master 1 polls each of the nodes 2, 3, and 4 while the corresponding nodes 2, 3, and 4 set the communication status flag when the communication is normal, and clears the communication error. Set the address of 2,3,4 to the first node (2,3,4), while the communication error node (2,3,4) is used when calling the communication error node (2,3,4). ) Is assigned to the first node (2, 3, 4).

Then, the current polling mode is set to the mode of calling the nodes 2, 3, and 4, which are normal communications. When the mode of the normal communication calls the nodes 2, 3, and 4, the node 2, which is a communication error, Switch to calling mode 3,4).

After that, the first node (2, 3, 4) is called and each node (2, 3, 4) waits for a response, and if there is no response from the corresponding node (2, 3, 4) within the set time The nodes 2, 3, and 4 deal with a communication error.

Then, the time required to call all the nodes (2, 3, 4) is set, and the first node (2, 3, 4) is called again only after the set time has elapsed.

Here, the operation of the master 1 will be described with reference to FIG.

First, the master 1 processes the data received from each node 2, 3, 4 as an interrupt, and determines whether this interrupt is caused by a communication error.

At this time, there is no response within the time set by each node (2, 3, 4) and the corresponding node (2, 3, 4) is treated as a communication error. This is a reception interrupt that occurs when the data sent to the master (1) is received.

Thereafter, the communication status flags of the nodes 2, 3, and 4 are set, which indicates that the nodes 2, 3, and 4 are in communication normal.

Here, the master 1 stores the input port data of the nodes 2, 3, and 4 received by the nodes 2, 3, and 4, and selects the nodes 2, 3, and 4 whose polling mode is normal for communication. It is determined whether the calling mode or the communication error nodes 2, 3, and 4 are called.

If the normal call is in the call mode, the communication flag of the call is cleared. Then, the master (1) is the address of the next call node (2, 3, 4) among the nodes (2, 3, 4) in which communication is normal. If all the nodes (2, 3, 4) which are normal communication are called, call nodes (2, 3, 4) which are communication errors.

Then, the master 1 sets the nodes 2, 3, and 4 to be called among the nodes 2, 3, and 4 when the polling mode is currently completed. Call the nodes 2, 3, and 4 according to the value larger than the address of 3, 4, and when the time required to call all the nodes 2, 3, and 4 elapses, the first node 2, Call 3,4).

At this time, the operation of the nodes 2, 3, and 4 will be described with reference to Fig. 13, and each node 2, 3, and 4 reads the data transmitted from the master 1, and the receiving station address of the data and its own. Determine if the addresses match.

If each node (2, 3, 4) does not match the recipient address and its address, it waits. On the other hand, if the recipient address and its address match, the node (2, 3, 4) waits for the data transmitted from the master (1). After outputting to the output port 80 managed by 2, 3, and 4, the state of the input port 79 managed by the corresponding node 2, 3, 4 is transmitted to the master 1, where FIG. Denotes a structure for a frame of data transmitted from the nodes 2, 3, and 4 to the master 1.

As described in detail above, the present invention enables communication between the master and each node using a single communication channel, thereby reducing the cost of wiring and having the effect of easily wiring and connecting the communication line. .

Claims (8)

A serial communication device in which one master having a communication device is in serial communication while polling 1: N with a plurality of nodes having a communication device, wherein the master and each node are connected by one communication line. Serial communication device. The master communication apparatus of claim 1, wherein the CPI is connected to a communication device through an address buffer, a data bus, and a control bus, and the CPI control bus is connected to a receiving port, and a transmitting terminal of the C communication device is connected to a transmitting port. And a receiving terminal of the communication element is connected to a receiving port, and is configured by connecting an output terminal of the receiving port and an output terminal of the transmitting port. The communication device of claim 1, wherein the communication device of the node is connected to a communication device via an address buffer, a data bus, and a control bus, and the control bus of the connection is connected to a receiving port, and a transmission terminal of the communication device is connected to a transmission port. And a receiving terminal of the communication element is connected to a receiving port, and is configured by connecting an output terminal of the receiving port and an output terminal of the transmitting port and connecting an input port and an output port to the CPI. Communication device. 4. The receiver of claim 2 or 3, wherein the receiving port connects an input terminal of a first signal receiving element connected to an output terminal of a transmission port, and connects an output terminal of the second signal receiving element connected to an address bus of the CPI and the input terminal. A serial communication device characterized in that it is connected to the control terminal of the signal receiving element. A first step of initializing the master; A second process of the master processing the data received from the node as an interrupt and transmitting and receiving data through one communication channel; And when the node receives data from the master, an interrupt is generated to perform a third process of transmitting and receiving data to and from the master through one communication channel. The method of claim 5, wherein the first process comprises: a first step (S1) of designating the number of all nodes; A second step S2 of initializing a flag for the communication state of each node to '0'; A third step S3 of setting an address of a node to be called currently as the first node; A fourth step S4 of setting the number of the communication error node as the first node; A fifth step (S5) of setting a mode of calling a node whose current polling mode is normal for communication; A sixth step S6 of calling the first node; A seventh step S7 of setting a time for waiting for a response from the node; And an eighth step (S8) of setting the time taken to call all nodes. The method of claim 5, wherein the second process comprises: determining whether a communication error interrupt has occurred (S21); Setting a communication state flag of a corresponding node if a communication error interrupt has not occurred in step S21; Storing input port data received at the node (S23); Determining whether a current mode is a polling mode (S24) when a communication error interrupt occurs in the step (S21); Clearing the communication flag of the corresponding device (S25) if the current polling mode is not present in the step (S24); Setting an address of a node to be called next among nodes in which communication is normal (S26); Judging whether the call of the node having normal communication is completed (S27); In step S28, invoking the node selected in step S26 if the call of the node having normal communication is not completed; Setting (S29) a mode in which a node in which communication is normal is called; Setting a time for waiting for a response from the node and terminating it (S30); Setting the communication error mode to a mode in which the call of the nodes (2, 3, 4) in which communication is normal is completed (S31); Setting a node to be called from among communication error nodes (S32) in the current polling mode (S24); Judging whether the call of the communication error node has been completed (S33); Calling (S34) the communication error node selected in the step (S33) if the call of the communication error node is not completed in the step (S33); If the call of the communication error node is completed in step S33, calling the node with a value greater than the address of the last node; Initializing an address to be called among the communication error nodes to '0' (S36); Determining whether a time period for calling all nodes has elapsed (S37); If the time taken to call all nodes has not elapsed in step S37, returning to step S30 and if the time taken to call all nodes has elapsed, setting the number of the node to be called as the first node. (S38); And setting the time taken to call all nodes and returning to the step (S39). The method of claim 5, wherein the third process includes: reading data transmitted from a master (S51); Determining whether the address of the receiving station and its address match (S52); Terminating if the receiving station address and its address do not match in step S52 and outputting data transmitted from the master to an output port managed by the node if the receiving station address and its address match; And transmitting the state of the input port managed by the node to the master and terminating (S54).