JP2770641B2 - Multiplex communication equipment for instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an instrument multiplex communication apparatus which does not affect the display of an instrument even if a delay occurs in data transmission for multiplex communication.

[0002]

2. Description of the Related Art In recent years, most devices mounted on vehicles have been driven by electric control. In the near future, the number of devices will increase with the installation of navigation systems, etc.
There is a trend of enhancement and increase in audio equipment, etc., but with this, the harness arranged in the car also becomes considerable,
This is one of the problems in this field aiming at reducing the weight of the vehicle body and reducing the size of the vehicle device. For this reason, a signal transmission method using multiplex communication has been devised. This is 1
Connect multiple devices to the book data bus, and between each device,
Data is transmitted and received via this data bus. Some of these data are important, and the data is prioritized so that the data with the higher priority is transmitted and received first. This may be, for example, a turn-on signal, but when this data is transmitted, other data is not transmitted until a data bus becomes available.

[0003]

By the way, data used for, for example, an instrument for a vehicle is set with a relatively low priority. When an engine tachometer is taken as an example here, besides displaying the engine speed, it may be used as one means for indicating whether the engine is good or not, so If the high data occupies the data bus and the data on the engine speed cannot be transmitted in a timely manner, the transmission of data will naturally have a time delay, that is, unnatural movements in changes in the pointer or display indicating the speed. Will happen. Although this is a problem caused simply by using multiplex communication, it is quite possible for a driver who is not aware of such circumstances to consider this movement as a movement due to a malfunction of the engine. This is not preferable.

[0004]

For SUMMARY OF THE INVENTION The present invention is to solve the above problems, and the meter device, the respective devices distributed arrangement including a measuring device for generating data to be processed in this instrument device, the An instrument multiplex communication device for connecting each device by a data bus and multiplexing data of each device, wherein
Data transmitted from the measuring device to the measuring device at a predetermined cycle.
A storage circuit for storing data, and a process for generating the predetermined period.
A logic circuit and the data transmitted from the data bus.
The signal waiting time has become longer than the data transmission cycle
The data from the storage circuit based on the predetermined period.
And a readout circuit for reading out data.

[0005]

The data transmitted from the measuring device for measuring instrument data to the measuring device via the data bus is stored in a storage circuit in the measuring device. This storage circuit stores the data in a time-division manner, and processes the data stored at regular intervals as data for display in order from the oldest one. Since the processing time is a fixed time interval, the unnaturalness of the display movement is eliminated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a multiplex communication system configuration, in which a plurality of devices are connected to one loop-shaped data bus 1. This device measures one cycle of a pulse (hereinafter referred to as a TA pulse) output from an ignition coil to measure the number of revolutions of an engine, and transmits the measured data as a data to an instrument device. It is an instrument device 3 or the like that displays a rotation speed, a vehicle speed, and the like based on data.

The instrument device 3 is as shown in FIG. First, data transmitted from the data bus 1 to the meter device 3 is output to the interface circuit 4. The interface circuit 3 determines whether the data is for the instrument device 4,
These are determined from information given to specific bits of data (not shown) such as parity check and data distribution, and data is distributed to each processing circuit. The data sorted for displaying the rotation speed is output to the storage circuit 5, which is a main part of the present invention. FIG. 2 shows a processing circuit 6 relating to the engine speed. Data is stored in the storage circuit 5, and the data is taken out and processed in the oldest order at regular intervals of the processing circuit 6. Reference numeral 7 denotes a read circuit for extracting the oldest data from each register of the storage device 5.

FIG. 3 shows a timing chart from the generation of a TA pulse to the processing of data based on the TA pulse. First, the engine speed measurement device 2 measures one period of the periodically generated TA pulse for each measurement period TS to obtain data n1, n2, and n3.

The data n1, n2 and n3 are transmitted to the data bus 1 at the same cycle TS as the measurement cycle TS and output to the meter device 3 via the data bus 1. Processing time delay t0,
Further, the data is transmitted with a time delay such as a transmission waiting time t1 for transmitting data with a higher priority in priority.

Thereafter, these data n1, n2, n3 are output to the storage circuit 5 and stored. This storage circuit 5 is composed of several registers, and is a shift register for sequentially transferring old data to the next register at every time TS.

After the storage circuit 5 stores the data n1, 2
After × TS time, the processing based on this n1 is performed by the processing circuit 6, and the engine speed is displayed. Thereafter, the processing circuit 6 executes processing based on the data n2 and n3 every time the TS time elapses. The reason why the processing cycle is long only for the processing of the data n1 is a processing for ensuring that data is stored in the storage circuit 5.

If the data in the storage circuit 5 is normal, the data is stored as the latest data from the right register to the left register. However, when the transmission waiting time t1 becomes longer than the transmission cycle TS, there is a register in which no data is stored.
At this time, data is transferred to the right register by the read circuit 7. This circuit 7 is also a circuit for reading out the data in the rightmost register storing data and processing it as processing data when there is no room for transition.

When the above processing is repeated, the TA pulse a becomes A
Thus, the TA pulse b is processed and displayed in B. If processing is performed according to the reception timing, data n2 is received after TS + t1 after receiving data n1, and data n3 is received after TS.
, Which has caused unnatural movements in the display. However, by providing the storage circuit 5, the data n
Since the processing time from the processing time 1 to the data n2 is TS, the processing can be performed at a constant cycle.
No unnatural movements occur. TA pulse a,
Although the data n1 and n2 are processed 2 × TS after the occurrence of b, since the period TS is about several msec, there is no display that is far from the current engine speed.

It is needless to say that the present invention is applicable not only to the measurement of the engine speed of a vehicle, but also to all the processing circuits of instruments which must display information in a timely manner, such as ships and aircraft. Although the data is obtained by measuring the period of the TA pulse, the data may be obtained by a gate time method of measuring how many TA pulses are output during the measurement period TS. The storage circuit 5 may be any circuit that can sequentially store data and output the data to the processing circuit 6 in chronological order, and is not limited to the shift register type.

[0015]

The present invention exhibits a meter device, distributes placing each device including a measuring device for generating data to be processed in this instrument device, each connected to the respective device by the data bus An instrument multiplex communication device for multiplex communication of data of the device, wherein the instrument device is provided with a predetermined cycle from the measurement device.
A storage circuit for storing data to be transmitted, and the predetermined cycle
And a processing circuit for generating the data transmitted from the data bus.
The data signal waiting time is longer than the data transmission cycle.
When it becomes larger, the memory circuit is reset based on the predetermined period
And a readout circuit for reading the data from the memory, whereby the processing time is ensured at a constant time interval, and the unnaturalness of the display movement is eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a multiplex communication system configuration.

FIG. 2 is a block diagram showing the inside of the meter device 1 of FIG. 1;

FIG. 3 is a timing chart until data based on a pulse of an ignition coil indicating an engine speed is processed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Data bus 2 Measuring device 3 Instrument device 5 Storage circuit 6 Processing circuit 7 Reading circuit

Claims (1)

(57) [Claims] And 1. A meter apparatus, the data of the instrument including a measuring device for generating data to be processed by the device the dispensed placing each device connected to the apparatus the respective device by the data bus a meter for multiplex communication apparatus for multiplex communication, before
Sent from the measuring device to the meter device at a predetermined cycle
A storage circuit for storing data, and generating the predetermined period
A processing circuit; and the data transmitted from the data bus.
Signal waiting time is longer than the data transmission cycle
The data from the storage circuit based on the predetermined period.
And a readout circuit for reading the data.
Instrument multiplex communication device.