JPH0541700A - Automatic detection device for communication data - Google Patents

Abstract

PURPOSE:To automatically detect the bit length and parity on the transmission at the time of asynchronous serial communication between a personal computer A and a printer B. CONSTITUTION:From the personal computer A, ASCII codes 1 and 5 are transmitted. A reception part 3 of an automatic detection device 1 receives the data with 8-bit length and without parity. The ASCII code is 8 bits, and its 1 and 5 are uneven and even numbers respectively when the number '1' in the binary notation. Therefore, two data received on a printer B changes according to the different combinations corresponding to the setting on the personal computer A. The control part decides the setting of the personal computer based on the received two data, setting the data length and parity of the reception part according to this.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in another device for performing asynchronous serial communication with one device and automatically detects the bit length and parity of communication data from one device. The present invention relates to an automatic detection device for communication data that can be used.

[0002]

2. Description of the Related Art Generally, when devices having an asynchronous serial communication function are connected to exchange data, the bit length, parity bit, stop bit, etc. of communication data must be matched. There wasn't.

[0003]

Conventionally, unless one knows in detail about the communication format setting of both devices,
There is a problem that it is difficult to set them all the same.

It is an object of the present invention to enable the receiving side to automatically detect the communication format of the transmitting side when asynchronous serial communication is performed between two devices.

[0005]

An automatic detection device for communication data according to the present invention is provided in another device which performs asynchronous serial communication with one device, and is transmitted from the one device. A receiving unit that receives an even number of test data having "1" and an odd number of test data having "1" without an 8-bit length parity, and a mode of change of the test data received by the receiving unit. From the transmitting side to a control unit for judging the bit length and the parity.

[0006]

From one device, test data having an even number of "1" s and test data having an odd number of "1s" are transmitted. These data are received by the receiving unit of the present apparatus in the state where the 8-bit length is not parity. Since the variation of the received data has regularity, the control unit detects the bit length and parity of the communication data on the transmission side based on this rule.

[0007]

EXAMPLE An example will be described with reference to FIGS. In FIG. 1, a personal computer A, which is one device, is connected to a printer B, which is the other device, so that asynchronous serial communication can be performed.

The printer B has a communication data automatic detection device 1 and a printing unit 2. The automatic detection device 1 has a receiving unit 3 that receives serial data transmitted from the personal computer A in an 8-bit length / non-parity state and converts the serial data into parallel data. The setting of the communication format of the receiver 3 can be arbitrarily changed by a signal from the controller 5 described later.

The automatic detection device 1 stores a data received by the receiving unit 3, and a control unit 5 for detecting the data length and the parity of the data from the personal computer A based on the data in the storage unit 4. And have. Further, the control unit 5 may output a communication format setting signal to the receiving unit 3 according to the detection result, and make the data length and the parity setting of the receiving unit 3 match the data from the personal computer A. You can do it.

Further, the printing unit 2 is connected to the control unit 5 of the automatic detection device 1 and can print data from the personal computer A asynchronously.

Next, the operation of the above configuration will be described. First, before starting the communication between the personal computer A and the printer B, the 8-bit AS is transferred from the personal computer A to the printer B.
Two pieces of test data are transmitted by the CII code. These test data are assumed to be an even number of "1" and an odd number of "1" when considered in the binary system. For example, A
"5" of the SCII code (35H = 00110101
B, 1 is 4) and “1” (31H = 00110001)
B and 3 are 3) are sequentially transmitted as test signals.

As shown in step 100 of FIG. 2, the test data is received by the receiving unit 3 in the state of 8 bits long and without parity, and is converted into parallel data.

As shown in step 101, the data of "even number 1" and the data of "odd number 1" are read into the storage unit 4.

As shown in steps 102 and 103, the data read into the storage unit 4 is examined by the control unit 5 to determine the bit length and the parity of the transmitted data. That is, there is a certain regularity in how the received data is garbled, depending on each setting of the personal computer A on the transmitting side.

As shown in FIGS. 3 and 4, when the transmitting side has a 7-bit length and no parity (7N), the 8th bit of both received data can be transformed into "1". When the transmitting side has a 7-bit length and even parity (7E), the 8th bit of the ASCII code 1 in which two "1" s are odd numbers can be transformed into "1". When the transmitting side has a 7-bit length and odd parity (7O), the ASCII code 5 is an even number of "1" s out of the two received data.
The 8th bit of is garbled to "1". If the transmitting side has the same 8-bit length and no parity (8N) as the receiving side, both received data can be read with correct values.

ASC transmitted as test data
Since the II code is 8 bits and the receiving side receives 8N, if the setting of the transmitting side is different as shown in FIG. 4, the same combination of two received data on the receiving side does not occur. .. Therefore, the set value on the transmission side can be correctly determined.

Next, as shown in step 104 of FIG. 2, the controller 5 sends a signal to the receiver 3 to set the data length and parity of the receiver 3 from the personal computer A judged in step 103. Match the data.

Next, as shown in step 105, the control section 5 sends a signal of reception preparation completion to the personal computer A side. With this, the personal computer A and the printer B can perform correct communication. Further, if the personal computer A changes the setting of the communication data, the printer B can automatically reset the communication format by this automatic detection device. In addition,
Although the above description did not mention the communication speed of the device, it must be set correctly.

In the above-described embodiment, the personal computer and the printer are exemplified as the device for performing the asynchronous serial communication, but the same automatic detection device can be applied to the communication between the personal computers. Further, it is not limited to a personal computer but can be widely applied to data communication between various industrial devices. For example, a machine tool having a movable table may be provided with a length measuring device for positioning a work, controlling the table position, and the like. Conventionally, the receiving format of the length measuring device was set according to the data output by the control unit of the machine tool. It becomes unnecessary, and it becomes possible to equip various types of machine tools with the same length measuring device.

[0020]

According to the present invention, since the bit length and parity bit of communication data can be automatically detected by the data output from the other party, a correct connection can be made without knowing details of the other party to be connected. Can be done.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an example.

FIG. 2 is a flowchart showing an operational sequence of the embodiment.

FIG. 3 is a diagram showing that the same data changes on the receiving side according to the setting on the transmitting side in the embodiment.

FIG. 4 is a table showing correspondence between set values on the transmitting side and received data on the receiving side in the embodiment.

[Explanation of symbols]

 A PC as one device B Printer as the other device 1 Automatic detection device for communication data 3 Receiver 5 Controller

Claims (1)

[Claims] 1. A test data having an even number of "1" s and an odd number of "1s" which are provided in another device which performs asynchronous serial communication with one device and which are transmitted from the one device. And a control unit for determining the bit length and the parity of the transmission side from the change mode of the test data received by the receiving unit. Automatic detection device for communication data.