JPS60206242A - Communicating method - Google Patents

Abstract

PURPOSE:To reduce the time loss on a serial transmission packet exchange type communication by transmitting the preamble of a response frame continuously at a reception side until the receiver response message of a command is set up, and monitoring the arrival of the response frame through a timer at a transmission side. CONSTITUTION:A communication line interface LIF sends and receives data through a communication line and an internal bus interface part BIF sends and receive data to and from the data processing part in a station. The preamble is provided at the head of the response frame R1, the response message rm comes next, and a postamble po is provided at the tail. A slave station once receiving the command starts sending the preamble mechanically and firstly regardless of the contents of the command. A master station sets a proper time limit value in the timer on the basis of a time tp and then decides whether there is a response or not. The time limit value of the timer is settable to an irreducible necessary value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] Mizumoto, J., relates to an improvement in a communication method in serial transmission packet switching communication.

In this type of communication, stations that have the functions of a master station, a slave station, or both are connected by white oil (F) wires, and the master station sends a command frame to one of the slave stations. The slave station sends a response frame back to the master station.The master station
When a command frame is sent, a timer monitors the arrival of a response frame from the slave station to determine whether there is a communication abnormality.

There are two types of response frames that the SLE 1 station sends back: a simple response and a data-ready response, and the latter requires data preparation and therefore takes more time to return the response.

<Conventional Example> When these two types of responses coexist, in order to monitor their arrival using a timer, either set the timer's time limit to match the expected maximum response time of the response with data, or Although the time limit value of the timer is determined separately depending on the type of response specified by In addition, determining the time limit value of the timer according to the contents of the command complicates communication control at the master station.

[Object 1] An object of the present invention is to provide a communication method that reduces time loss and makes it easy to control communication at a master station when monitoring response return times using a timer. It is in.

<Key Points> In serial transmission packet switching communication, the receiving side receives the 1ltW response message after receiving the command.
One of the above objectives has been achieved using a communication method characterized in that the preamble of the response frame continues to be transmitted until the command is completed, and the transmitting side monitors the arrival of the response frame using a timer after transmitting the command.

<Example> Hereinafter, the present invention will be explained in detail with reference to Examples.

Fig. 1 is a conceptual diagram of a communication system to which the present invention is applied, Fig. 2 is a conceptual diagram of main parts of a communication station, Fig. 3 is a communication transition diagram in an embodiment of the present invention, and Fig. 4 is a conceptual diagram of the present invention. FIG. 3 is an explanatory diagram of the operation of the embodiment.

Configuration> In Figure 1, 81.82. S3... are communication stations connected by communication lines, one of which serves as a master station and the others serve as slave stations.

Each communication station S1 has a communication control section as shown in FIG. 2, and controls communication between the communication line L and the data processing section within the station.

In FIG. 2, LIF is a communication line interface section, BIF is an internal bus interface section, and CNT is a control section. The communication line interface LIF sends and receives data to and from the communication line L, and the internal bus interface BIF sends and receives data to and from the data processing section in the station. The control unit CNT controls the operations of these interfaces and executes communication based on predetermined procedures. The control unit CNT is configured by firmware having a microprogram.

The communication procedure is shown in the state transition diagram of FIG.

In FIG. 3, (a) is a state transition diagram of the master station, and (b) is a state transition diagram of the slave station.

The state transition of the master station is transmission preparation 1
11 IN transmission length: 2m, response length: 3m, preamble reception: 4m, response reception: 5m, postamble reception: 1 word, 6IIl.

The state transition of the Threshi station is waiting for reception 1
s, reception 28. Response preparation 3sq Response 4s.

There is a response end 5S.

The master station's transmission 2Il is a condition for the slave station's transition from reception waiting 1S to reception (= 28).The master station's response hold 3m is a condition for the slave station's transition from reception 2S to response?t4Wa3s. .Slave station response preparation 3
S is a condition for transition from the master station's response hold 31 to preamble reception 4m. The slave station's response 45 becomes a condition for transition from the master station's preamble reception 4m to response reception 5Ill.

The slave station's response end 5S is a condition for transition from the mask station's response reception 51 to postamble reception 6m.

The response frame is configured by adding a preamble and a postampule before and after the response message. Then, in response preparation 3S of the slave station, a preamble is transmitted, a response message is transmitted in response 4S, and a postamble is transmitted in response end 5S. Transmission of the preamble begins immediately upon completion of reception of the command frame and continues until the response message is ready. The master station sets a timer with a response time of 3 m to notify the arrival of the preamble, and if the preamble arrives before time-up, the preamble is received at 4 m.
However, when the time-up occurs, it is determined that there is a communication error and the transition is made to 1m of preparation for transmission.

<Operation> The operation of the embodiment of the present invention configured as described above is as follows. An explanatory diagram of the operation is shown in FIG.

The master station sends a command frame C1 (g
=l-, the slave station returns a response frame R1 in response.

The first part of the response frame R1 is the preamble pr, the next part is the response message "m, and the last part is the postamble pO. When the slave station controller receives a command, it automatically first reads the preamble, regardless of its contents. Therefore, the time tp from when the master station finishes transmitting the command frame C1 until it receives the response frame R1 is determined by the configuration of the communication system and is a nearly constant value that is unrelated to the content of the command or response. Since the preamble p continues until the response message is ready, the length of the preamble p is not constant.For example, it may be longer as in response frame R2, but the time when the preamble arrives tp does not change. Therefore, in the master station, by setting an appropriate time limit value in the timer based on time tp, it is possible to determine whether there is an abnormality in the response.

Since the time limit value of the timer can be selected to be the minimum necessary value regardless of the response message preparation time at the slave station, no time loss occurs as in the conventional case. Also, since only one type of timer value is required,
Communication control at the master station is simplified.

Effects> As described above, according to the present invention, it is possible to realize a communication method in which there is little time loss and communication control at the master station is easy when monitoring the response response time using a timer. .

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a communication system to which the present invention is applied, FIG. 2 is a conceptual diagram of main parts of the communication station in FIG. 1, and FIG. 3 is a state transition diagram of an embodiment of the present invention. FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention. Sl, 82. S2...Communication station L...Communication line LIF...Communication line interface section BIF...
- Internal bus interface unit CNT...Control units C1, C3...Command frame 1-<1, R2...Response frame 11r
...British ampule rm...Message 110...Postamble Figure 1 Nail Figure 2

Claims (1)

[Claims] In serial transmission packet-switched communication, the receiving side continues to send the preamble of the response frame after receiving the command until the response message is ready, and the sending side uses a timer to detect the arrival of the response frame after sending the command. The i-method is characterized by the ability to monitor