JP3259518B2 - Display data transmission device for measuring instruments - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display data transmission apparatus for a so-called separate display type measuring instrument in which a display section is separated from, for example, an apparatus main body.

[0002]

2. Description of the Related Art In measuring instruments such as electronic balances and counting scales, conventionally, there are three methods of transmitting display data from a main body of a measuring instrument to a separate display unit: parallel transmission, synchronous serial transmission, and asynchronous serial transmission. is there.

[0003]

By the way, the above 3)
Of the two transmission methods, the parallel transmission method has an economical problem because the number of wirings is large.

On the other hand, in the serial transmission methods and
Although data transmission can be performed with about two or three signal lines, the asynchronous serial transmission method among these serial transmissions has a disadvantage that the transmission rate cannot be increased so much from the viewpoint of noise resistance.

On the other hand, in the synchronous serial transmission system,
Since one-bit information can be handled by one clock as a synchronization signal, it is possible to increase the transmission rate by increasing the clock speed. However, if a noise component is included in the synchronization signal during the transmission process, There is a disadvantage that a bit shift occurs on the receiving side (display side) and data cannot be transmitted accurately. For this reason, at present, transmission cables cannot be made too long. In practice, when this type of measuring instrument body and indicator is used in a factory or site, the cable length between them is several TTL levels. m is the limit.

The present invention has been made in view of such circumstances, and is a device which basically employs a synchronous serial transmission system and which does not substantially display an erroneous display even if a bit shift occurs due to noise. It is an object of the present invention to provide a display data transmission device.

[0007]

In order to achieve the above object, according to the present invention, as shown in a basic conceptual diagram of FIG. 1, display data is sent to a transmission path L as a serial signal to a measuring instrument body So. A data transmitting section a, a character adding section b for adding at least two consecutive synchronizing characters to one frame of data transmission of the display, and a clock for synchronizing a signal transmitted to the transmission line L; And a synchronizing signal generator c for setting a specific section Q (see FIG. 4) in which the signal level of the synchronizing signal does not change for two clocks or more after the continuation of the synchronizing character is completed,
The synchronization characters added by the character addition unit b are hexadecimal codes equal to each other, and are 00H, 55H, and AA.
H, FFH, CCH or 33H is set.

[0008] The serial signal transmitted through the transmission line L is transmitted to the display side Si based on the synchronization signal.
One bit is taken for each clock, and this one
A comparison unit d that combines the bit information with the previously acquired 7-bit information and sequentially compares whether or not the 8-bit information matches the code of the synchronization character, and detects a specific section Q of the synchronization signal Detecting section e and data collecting section f
After the data acquisition of the first frame of the serial signal is completed, the data acquisition unit f acquires the data after the comparison result matches and the specific section Q is detected. Characterized by being configured to start.

[0009]

In the transmission apparatus of the present invention, the two synchronization characters contained in one frame of the display are the same hexadecimal code, and the code is set to 00H 0,0,0,0,0,0,0,0. given that,
For example, when the bit shift is 1 bit, as shown in FIGS. 3 and 4, when the first 1-bit information of the second synchronization character C2 is fetched, the 1-bit b8 and the previous bit b8 are taken. Since the 8-bit information including the 7 bits b1... B7 coincides with the code [00H], the synchronization character is recognized at this point. Thereafter, the signal level of the synchronization signal is set to Hi or Lo for two clocks or more. Until the detection (specific section Q) is detected, the bit information cannot be taken in. Then, the bit information is started to be taken when the next synchronous clock is sent.
Therefore, a bit shift occurring before the two synchronization characters C1 and C2 is eliminated (absorbed) in the section between the two synchronization characters, and normal transmission is performed thereafter.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of the embodiment of the present invention.

The control unit 10 of the measuring instrument body 1 includes a CPU 1
1, a ROM 12, a RAM 13, an input / output interface 14, and the like. The control unit 10 includes a measurement unit 15
And the switches 17 are connected, and further, the three-wire synchronization interface 16 is connected. The display 18 can also be connected to the control unit 10 on the main body side.

On the other hand, the control unit 20 of the display unit 2 also includes a CPU 21, a ROM 22, a RAM 23, an input / output interface 24, and the like. The interface 26 is connected.

The measuring instrument body 1 and the display section 2 are
The two 3-wire synchronization interfaces 16 and 26 are
X-rays, synchronization (SYNC) lines, and Rx lines are connected to each other, and signals are transmitted by so-called three-wire synchronous communication.

Here, the RO of the control unit 10 on the measuring instrument main body side is used.
M12 includes, in addition to a program for arithmetic processing generally performed by this type of measuring device such as processing of an output signal of the measuring unit 15, output of display data and its synchronizing signal (SYNC signal), which will be described later, and a synchronizing character C1. , C2 are added.

The ROM 2 of the control unit 20 on the display unit side
As described later, a program for processing signals transmitted through the Tx line and the synchronization line, transmitting signals to the Rx line, and controlling the driving of the display 25 is written in the memory 2. I have.

Next, the operation of the embodiment of the present invention will be described with reference to the timing waveform charts of FIGS. The address and data are sent from the measuring instrument body 1 to the display section 2 to the Tx line in synchronization with the SYNC signal. Display unit 2
Signals such as information input by operating the keyboard 27 on the side are transmitted to the measuring instrument main body 1 through Rx lines. The signal on the Rx line is also synchronized with the SYNC signal. However, even when the signal is transmitted through the Rx line, the SYNC signal is sent out from the measuring instrument body 1.

In this example, as shown in FIG.
The required number of address and data sets A0 and D0
An and Dn and two synchronous characters (for example, the same code 00H) C1 and C2 are sequentially sent out for one frame of display (see FIG. 5A). Also, in the SYNC signal sent out to the synchronization line, a specific section Q in which the Hi signal level continues for at least two clocks after the continuation of the two synchronization characters C1 and C2 is set (see FIG. 4). .

If a bit shift of one bit occurs on the SYNC line (noise is mixed at point P1 in FIG. 3), the address An and data Dn are transmitted to the display unit 2 as erroneous information. And the display is incorrect or not displayed.

However, in this example, since two synchronization characters C1 and C2 of code 00H are transmitted following data Dn, if there is a one-bit shift in synchronization, as shown in FIG. When the first 1-bit information of the second synchronization character C2 is taken in, the 1-bit b
The 8-bit information, which is the sum of 8 and the previous 7 bits b1... B7, matches the code [00H], at which point the synchronization character is recognized (point P2).

Next, when the display unit 2 recognizes the synchronization character, it checks whether the SYNC signal is in a high state for more than two clocks (point P3). The signal level is set to Lo (point P4) and R
When x = Lo, the measuring instrument main body 1 again outputs the SYNC signal.
The signal level is set to Lo (point P5), and the next frame is started (point P6).

With the above operation, the bit shift generated at the point P1 is eliminated in the section between the two synchronization characters C1 and C2, and the display data can be transmitted in the next frame without any bit shift (SYNC shift). A correct image can be displayed on the display side.

When the display unit 2 recognizes the synchronization character, it takes in 1-bit information for each SYNC clock 1 and, when 8 bits have been collected, the information is converted to the code of the synchronization character. A comparison is made as to whether or not they match. If they do not match, the process of discarding the oldest 1 bit, adding the next fetched bit, and performing comparison is sequentially repeated. If 00H or FFH 1,1,1,1,1,1,1,1 is adopted, the SYNC shift in the range of 1 to 7 bits can be corrected in units of 1 bit. In addition, 5
5H 0,1,0,1,0,1,0,1, AAH 1,0,1,0,1,0,1,0,
CCH 1,1,0,0,1,1,0,0 or 33H0,0,1,1,0,0,1,
When 1 is adopted, the SYNC shift can be corrected in units of 2 bits. When the SYNC shift reaches 8 bits, it goes without saying that normal transmission is performed without the above processing.

In the above embodiment, if the SYNC frequency is set so that the transmission speed is 0.1 second or less per frame (possibly 0.05 seconds), an erroneous image is not left in the eyes. Can be convenient.

Although the above-described embodiment employs the three-wire synchronous communication system, the present invention can be practiced even without the Rx line. In this case, the second synchronous character C2 is used.
, The display unit 2 should wait for a time sufficient for the SYNC signal to recognize the Hi state (point P3) and then proceed to points P5 and P6.

In the above embodiment, SYNC =
Although the case of H active (Lo except during data transmission) is shown, the sign of the logic may be reversed.
However, between the two synchronization characters C1 and C2,
The sign of the specific section Q following the synchronization character C2 is always reversed.

Further, in the above embodiment, the synchronization character is provided at the end of the frame. However, the present invention is not limited to this. For example, the synchronization character may be provided at the beginning of the frame as shown in FIG. Or another location. However, if the purpose is to insert a synchronization character as a break between display data (information) groups for one frame, it is provided at the end of the frame. Also, 1
The number of synchronization characters inserted into the frame may be three or more. Furthermore, the address information is not particularly necessary and can be omitted according to the design concept.

The display data transmission device of the present invention has a structure in which a measuring device main body and a display device are incorporated in the same device, and the distance between the measuring device main body and the display device is relatively long, in addition to the separate measuring device. Can also be used for measuring instruments.

[0028]

As described above, according to the display data transmission apparatus of the present invention, at least two synchronization characters are inserted into one display frame of a series of display data sent from the measuring instrument body, and the synchronization is performed. After detecting a synchronization character for one code in the character section, the synchronization signal line is used as a handshake line. Therefore, even if a bit shift occurs during transmission, normal display can be performed in the next display frame.

Further, according to the present invention, when a temporary disconnection occurs in the synchronization signal line between the measuring instrument main body and the display side,
By simply performing the reconnection, synchronization can be achieved after the next synchronization character after the connection, and the effect of continuing transmission of the image can also be achieved.

[Brief description of the drawings]

FIG. 1 is a basic conceptual diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 3 is a timing waveform chart showing the operation of the embodiment.

FIG. 4 is a timing waveform chart of the same.

FIG. 5 is a diagram schematically illustrating a signal transmission mode according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measuring instrument main body 10 Control part 15 Measurement part 16 Three-wire synchronous interface 2 Display part 20 Control part 25 Display 26 Three-wire synchronous interface C1, C2 Synchronous character

Claims (1)

(57) [Claims] 1. An apparatus for transmitting display data from a measuring instrument main body to a display via a transmission path, wherein the measuring instrument main body includes a data transmission section for transmitting display data to the transmission path as a serial signal, A character adding unit for adding at least two consecutive synchronization characters to data transmission for one frame of a frame, a clock for synchronizing a signal sent to the transmission line, and a signal level for the synchronization signal A synchronous signal generating unit for setting a specific section in which the synchronous character does not change for two clocks or more after the continuation of the synchronous character is completed, wherein the synchronous character added by the character adding unit is a hexadecimal code equal to each other,
00H, 55H, AAH, FFH, CCH or 33
H is set to any code, and the display side incorporates the serial signal sent through the transmission line one bit at a time based on the synchronization signal, one bit at a time. A comparing unit that combines the collected 1-bit information with the previously acquired 7-bit information and sequentially compares whether the 8-bit information matches the code of the synchronization character, and a specific section of the synchronization signal And a data sampling unit are provided, and after the data sampling of the first frame of the serial signal is completed, the data sampling unit matches the comparison result and detects the specific section. A display data transmission device for a measuring instrument, wherein the display data transmission device is configured to start taking data after the measurement.