JPH0424858A - Handshake system between host computer and tool - Google Patents

Abstract

PURPOSE:To surely secure the handshake between a host computer of a semidouble communication system and a tool which performs the multi-task processing by shortening the time-out period of the host computer compared with that of the tool. CONSTITUTION:A host computer 1 has its time-out setting time shorter than that of a tool 2. In other words, the time-out period (trs) of the tool 2 is longer enough than the time-out period (trq) of the computer 1. Thus the computer a never starts its time-out operation nor proceeds to its time-out processing before the response is returned from the tool 2 against the transmission of the response. In this case, however, the tool 2 does not receive the request sent from the computer 1 owing to the discontinuation of its time-out processing and receives only the response returned from the computer 1. Thus the handshake is recovered between the computer 1 and the tool 2.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a handshake method between a host computer and a tool, and is particularly suitable for use when a host computer is used to control an emulator for a one-chip microcomputer. It is something.

<Prior art> For example, when a host computer controls a one-chip microcomputer emulator (hereinafter referred to as a tool), the tool processes one request given from the host computer to the tool, Communication is carried out between the host computer and the tool to convey the results to the host computer.

Conventionally, communication for this purpose has been performed using a half-duplex communication method in which communication is performed alternately using two sets of transmission paths.

<Problems to be Solved by the Invention> The above tools are provided with various resources for data processing. In order to use these resources effectively, it is desirable to perform multitasking within the tool. However, when the tool is operated by multitasking, a situation may occur where both the host computer and the tool transmit data at the same time. In such a case, if a conventional half-duplex communication method using a common transmission path is used, handshaking between the two parties may become impossible due to data collision. For this reason, in the past, when communication was performed between a host computer and a tool using a half-duplex communication method, it was not possible to operate the tool in multi-task processing.

In view of the above-mentioned problems, the present invention ensures handshaking between the two parties even when the tool is operated by multitasking when the tool is controlled by the host computer while communicating using the half-duplex communication method. The purpose is to make it possible.

<Means for Solving the Problems> In the hunt shake method between a host computer and a tool of the present invention, communication is performed between the host computer and the tool using a half-duplex communication method, and the tool is controlled by the host computer. In this control method, the timeout time on the host computer side is set shorter than the timeout time on the tool side, and when the handshake between the host computer and the tool cannot be established, the host computer By causing the computer side to time out first and transitioning its operating state from the transmitting state to the receiving state, huntshaking between these two systems is ensured.

<Operation> Because the host computer's timeout setting is shorter than the tool's timeout setting, when handshake between the host computer and the tool cannot be established.

The host computer always times out first and switches its operation from transmitting operation to receiving operation. As a result, the transmission of requests from the host computer side is stopped, a state is reached in which only responses are received from the host combiator, and the huntshake between the host computer and the tool is restored.

<Embodiment> FIG. 1 is an explanatory diagram of the contents of communication performed between a host computer and a tool showing an embodiment of the present invention.

The tool 2 in this embodiment is an emulator for a one-chip microcomputer, and the communication method used between the host computer 1 and the tool 2 is a half-duplex communication method. In such a communication system, the tool 2 executes process (2) in response to a request reql from the host computer 1, and returns a response resl to the host computer 1. As shown in the request sequence explanatory diagram of FIG. 2, a request sent from the host computer 1 is always received within a predetermined request time treq after the request is sent, and the request sequence ends. .

As shown in the response sequence explanatory diagram of FIG. 3, a response is always received within a predetermined response time tres in response to the response transmission, and the response sequence ends.

FIG. 4 shows a flowchart of the request sequence on the host computer I side. In FIG. 4, the host computer 1 transmits a request in step P□, and then checks in step P2 whether or not a reply to the request has been received. Then, if a reply to the request is received, a reception operation for the reply to the request is performed. If no response to the request is received, proceed to step P3, and check whether the value of the timer that has started operating from the time the request was sent has exceeded a predetermined request time treq. If the request time treq or more has elapsed, timeout processing is performed. Furthermore, if the request time is within the predetermined request time treq, the server checks again to see if a reply to the request has been received.

As shown in the flowchart in Figure 5, 3
The flow of processing is also the same as that of the host computer 1 in Figure 4.
The flow of the process is the same as that of the previous example, but the difference is that in this case, the condition for performing the timeout process in step P3 is when a predetermined response time tres or more has elapsed.

Next, a specific method for implementing the handshake method between the host computer and the tool of this embodiment will be described.

As shown in Figure 1, multiple requests 1 to n are generated from the host computer 1, and the tool 2 processes them or multitasks, and the response from the tool 2 is sent asynchronously to the host computer. When the data is sent to side 1, a collision between the request from host computer 1 and the response from tool 2 always occurs in the half-duplex communication line, and the communication between host computer 1 and tool 2
You won't be able to get a hunt shake with.

Therefore, in this method, in order to restore the handshake between the host computer 1 and the tool 2, the following method is adopted. In other words, if the timer value treq (timer value tres) is used, and the host computer 1's request and the tool's response collide and a huntshake cannot be obtained, the host computer 1 side must always detect the timeout state first. ing.

When a timeout condition is detected, host computer 1
The side stops sending the request, moves on to receive the response sent from the tool 2, and sends a reply to the response to the tool 2.

After transmitting the response to the host computer 1, the tool 2 waits only for the response from the host computer 1.

When a request from the host computer 1 and a response from the tool 2 collide, the handshake between the host computer 1 and the tool 2 is restored as follows using the above method.

That is, when a predetermined request time treq has elapsed since the request from the host computer 1 collides with the response from the tool 2, the host computer 1 enters a timeout process and stops sending the request, and the request from the tool 2 Start receiving operation for response transmission. Then, the host computer 1 sends a reply to the request to the tool 2.

On the other hand, the timeout time tres on the tool 2 side is sufficiently larger than the timeout time treq on the host computer l side, so the host computer l enters the timeout operation and waits until the response to the response sent by the tool 2 is received. It will not proceed to processing. In this case, the tool 2 side is the host computer
Since it is waiting only for the response from the host computer 1, it does not receive the request transmission from the host computer 1 that was canceled due to timeout processing on the host computer 1 side, but only receives the response from the host computer 1. The handshake between host computer 1 and tool 2 is restored.

(Effects of the Invention) As described above, the present invention sets the timeout time on the host computer side to be shorter than the timeout time on the tool side when communicating between the host computer and the tool using the half-duplex communication method. However, when the huntshake between the host computer and the tool cannot be established, the host computer times out first and its operating state changes from the sending state to the receiving state, so it is half-secondary. It is possible to reliably perform handshaking between the host computer and the tool that performs multitasking processing using a heavy communication method.Therefore, processing within the tool can be performed by multitasking, so each resource within the tool can be It can be used effectively, and tools can be made more sophisticated, faster in processing speed, and more multifunctional.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of communication content between a host computer and a tool showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of a request sequence, FIG. 3 is an explanatory diagram of a response sequence, and FIG. 4 is an explanatory diagram of a response sequence. , a request sequence flowchart, and FIG. 5 is a response sequence flowchart. l...Host computer, 2...Tool. req...request, res...response. treq--predetermined request time. tres...predetermined response time. Patent applicant Oki Electric Industry Co., Ltd. Agent
Patent Attorney Noriku Funabashi /7/'
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figure

Claims (1)

[Scope of Claim] A control method in which communication is performed between a host computer and a tool using a half-duplex communication method, and the tool is controlled by the host computer, wherein a timeout period on the side of the host computer is controlled by the tool. When the handshake between the host computer and the tool cannot be established, the host computer times out first and the operating status of the host computer is received from the sending state. A handshake method between a host computer and a tool, characterized in that the handshake between the two is ensured by transitioning the host computer to the tool state.