JPH0433064B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data reception monitoring device in DMA transfer, and in particular, data reception monitoring for a frame format signal in which transfer data is sandwiched between two flags. It is related to the device.

Conventional data reception monitoring devices are only effective for signals with a certain frame format, and do not function accurately for signals with a frame format in which transfer data is sandwiched between two flags. This improvement was strongly requested.

[Conventional technology]

Conventionally, data frames for performing procedural control of a data communication control device are often configured in a frame format based on a predetermined transmission control procedure, and in this case, reception of data frames can be easily monitored.

However, when communicating with a communication control device that has a frame format that does not comply with this transmission control procedure, it is not possible to apply a data format reception monitoring method that is based on a predetermined transmission control procedure. Can not.

FIG. 3 is a diagram showing a frame format for basic data transmission.

FIG. 4 is a diagram showing a frame format based on the HDLC format.

FIG. 5 shows a format in which flags F are placed before and after the transferred data.

In the figure, STX is a frame start code, ETX is a frame end code, F1 is a start flag, F2 is an end flag, A is an address field, C is a control field, FCS is a frame check sequence, F is a flag, and DATA is data. .

Data frames for controlling procedures between data communication control devices are in a predetermined standard transmission frame format, such as the frame format for basic data transmission as shown in Figure 3, or the frame format as shown in Figure 4.
HDLC format is often used.

In these formats, data is inserted between the start code STX and end code ETX of the frame as shown in Figure 3, and data is inserted between the start flag F1, address field A, and control field C as shown in Figure 4. After that, a frame check sequence FCS and a termination flag F2 are placed so that data reception can be easily detected.

However, in order to deal with a communication control device that has a special frame format that does not comply with such a transmission control procedure, it is not possible to apply a data frame reception monitoring method based on a predetermined transmission control procedure. Can not.

For example, it has been impossible to oppose a communication control device having a format in which data DATA is simply sandwiched between two flags F as shown in FIG.

[Problem that the invention seeks to solve]

The object of the present invention is to provide a special frame format,
In particular, it is an object of the present invention to provide a data reception monitoring device capable of receiving and analyzing a data frame having the same frame structure sandwiched between two flag patterns.

[Means for solving problems]

The means to solve the problem is to monitor the data reception status of the DMA controller activated by receiving the flag from a signal in which data to be transferred is inserted between two flags at predetermined time intervals. The monitoring device is provided with a byte count register whose count value increments in accordance with the number of data to be transferred that has been taken in by the DMA controller, and a timer that operates for a time corresponding to the transfer time of the data to be transferred. The data reception monitoring device determines that the data to be transferred is being received if the count value of the byte count register is incrementing, and starts the timer if the count value of the byte count register has stopped incrementing. This is achieved by configuring the timer to proceed to the next process when the count value continues to stop advancing until the end of the operation of the timer.

[Effect]

In the data reception control using the DMA transfer method, the present invention monitors the value of the byte count register of the DMA controller so that it can be determined whether the data is being received or the reception has been completed. This brings about the effect that not only data frames based on standard transmission control procedures but also data frames having a special frame structure can be received and analyzed.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the operation of a data reception monitoring device according to the present invention.

In the figure, 1 is a communication control device, 2 is a main control device, and 3 is a communication control device.
is a DMA controller, 4 is an external interface, 5 is a data reception monitoring device, 6 is an external device, 3
a is a byte count register.

The details of the present invention will be explained below with reference to the drawings.

The transfer of the data format in which flags F are placed before and after the transfer data as shown in FIG. 5 will now be explained.

That is, data is received by DMA transfer, and the data reception monitoring device 5 according to the present invention samples the value of the byte count register 3a in the DMA controller 3 at all times from the data reception start state.

The DMA controller 3 takes in data other than flag F at the start of data reception, and the byte count register 3a counts data D and advances. After the byte count register 3a starts incrementing, if no change in the count value of the byte count register 3a is observed for a certain period of time corresponding to the data transfer time, the data reception monitoring device 5 determines that data reception has ended. Then, move on to the next data analysis process.

In this way, any data frame sandwiched between flag patterns F can be received and analyzed regardless of the format of the transmission control procedure.

FIG. 2 is a diagram illustrating the operation of the data reception monitoring device according to the present invention.

Note that "state 0" indicates a state before reception, "state 1" indicates a state in which preparation for reception is completed, "state 2" indicates a state in which data is being received, and "state 3" indicates a state in which data reception is completed. Also, BCR is an abbreviation for byte count register 3a.

The data reception monitoring device 5 checks whether it is in "state 0" or not, and if it is "state 0", it prepares to receive data and becomes "state 1".

If the status is not 0, the data reception monitoring device 5
Checks whether the state is 1 or not, and if it is "state 1", checks whether the byte count register 3a is incrementing or not, and if it is incrementing, it is "state 2".
Then, it is checked again whether the byte count register 3a is incrementing.

If it is not “state 1”, is it “state 2”?
If it is "state 2", then it is checked whether the byte count register 3a has stopped incrementing or not, and if no, it is checked again whether the byte count register 3a has stopped incrementing. Find out whether or not.

If it is stopped, a timer is set and the state is determined to be "state 3", that is, the state where data reception is completed.

If it is not “state 2”, the timer is 0 or
If it is 0, the process moves to the next data analysis process. If it is not 0, then the timer is 0 again or
Find out whether or not.

〔Effect of the invention〕

As explained in detail above, according to the present invention, not only data frames based on standard transmission control procedures, but also data frames with a special frame format, especially data frames with the same frame structure sandwiched between two flag patterns, can also be processed. It has the great effect of being able to receive and analyze information.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the operation of a data reception monitoring device according to the present invention. FIG. 2 is a diagram illustrating the operation of the data reception monitoring device according to the present invention. FIG. 3 is a diagram showing a frame format for basic data transmission. FIG. 4 is a diagram showing a frame format based on the HDLC format. FIG. 5 shows a format in which flags F are placed before and after the transferred data. In the figure, STX is a frame start code, ETX is a frame end code, F1 is a start flag, F2 is an end flag, A is an address field, C is a control field, FCS is a frame check sequence, F is a flag, DATA is data, 1 2 is a communication control device, 2 is a main control device, 3 is a DMA controller, 4 is an external interface, 5 is a data reception monitoring device, 6 is an external device, and 3a is a byte count register.

Claims (1)

[Scope of Claims] 1. Activated by receiving a flag from a signal in which data to be transferred is inserted between two flags.
A data reception monitoring device that monitors the data reception state of a DMA controller at predetermined time intervals includes a byte count register whose count value increments in accordance with the number of data to be transferred that has been taken in by the DMA controller, and a byte count register that increments a count value corresponding to the number of data to be transferred that has been taken in by the DMA controller; and a timer that operates for a time corresponding to the transfer time of the byte count register, and the data reception monitoring device determines that the data to be transferred is being received if the count value of the byte count register is incrementing, and the data reception monitoring device determines that the data to be transferred is being received. If the count value of the register has stopped advancing, the timer is set and it is determined that the reception of the data to be transferred has ended. However, if the count value continues to stop advancing until the timer ends, A data reception monitoring device characterized in that it is configured to move to the next process.