JPH0482448A - Transmission speed switching system - Google Patents

Abstract

PURPOSE:To prevent a dead operation occurring due to the forgetting of switching or a mistake by transmitting a command code from transmission side equipment, judging the transmission speed of the transmission side equipment based on a reception code, and switching the transmission speed to the one of the transmission side equipment. CONSTITUTION:When the transmission speed of a PC 1 is set, for example, at the one of two times that of a peripheral device 2, a sampling cycle to read a serial signal is doubled. Therefore, since a code is received for four times in two times of transmission of a command message, the CPU 1b of the PC 1 decides that the transmission speed of the device 2 is 1/2 the speed of a PC 1 side, and after the speed is switched to the same speed as that of a device 2 side, reception processing is performed. In such a way, it is possible to dispense with the operation of a specific switching means and to prevent mis- switching performed by judging the transmission speed of the peripheral device by the kind of a received and recognized code and identifying the transmission speed of a communication port.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a transmission rate switching method.

[Conventional technology]

As shown in FIG. 11, a programmable controller (hereinafter abbreviated as PC)1. When connecting R3 and peripheral devices
232C type communication boats are used to connect to each other, but normally the faster the transmission speed, the more data can be sent within a certain amount of time, so it is normal to communicate at a higher transmission speed. . However, when using a dedicated peripheral device 21 for PCI, the transmission speed can be set arbitrarily, and a high transmission speed such as 19.2 Kbps can be selected, for example. On the other hand, recently personal computers (
Personal computers (hereinafter abbreviated as personal computers) are increasingly being used, and in the case of peripheral devices 22 that are generally personal computers, the maximum transmission speed is often 9600 bps. Therefore, it is necessary to switch the transmission speed between when using the dedicated peripheral device 21 and when using the peripheral bag W2□ consisting of a personal computer.For this reason, a switching means such as a switch is provided on the PCI side, and the peripheral device to be connected is Operate at the same time.

[Problem to be solved by the invention]

As mentioned above, when switching the transmission speed depending on whether the peripheral device connected to the PCI is the dedicated peripheral device 21 or the peripheral device 22 consisting of a personal computer, the switching operation must be performed every time the peripheral device used is changed. It was annoying. If you forget to switch or make a mistake,
Since the device does not work, it is determined that the device is malfunctioning, and work stops, which is inconvenient in terms of usability. The present invention has been made in view of the above-mentioned problems, and its purpose is to automatically determine the transmission speed of the transmitting side device and switch the transmission speed of the receiving side device, so that it is possible to automatically determine the transmission speed of the transmitting side device and switch the transmission speed of the receiving side device. To provide a transmission speed switching method that eliminates switching operations and eliminates troublesome operations, forgetting to switch, and mistakes.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention has been developed to transmit data using a serial signal such as the R3232C method between two devices according to a predetermined procedure. A specific transmission speed switching command code is transmitted, and the receiving device transmits the received code when the receiving code read at a sampling period according to the set transmission speed of the receiving side is different from the above specific transmission speed switching command code. The transmission speed of the transmitting device is determined based on the transmission speed of the transmitting device, and the transmission speed is switched to that of the transmitting device.

[Effect]

According to the present invention, by sending a specific transmission speed switching command code from the transmitting device, the receiving device changes the transmission of the transmitting device according to the content of the receiving code that has changed according to its own set transmission speed. The speed can be determined, and as a result, the transmission speed of the receiving device can be automatically switched to the same transmission speed as the transmission speed of the sending device.

【Example】

The present invention will be explained below with reference to Examples. First, as shown in FIG. 1, the PCI using the present invention includes a CPU 1a that performs arithmetic processing, a ROM 1b that stores system programs, etc., a RAM 1c that stores a user's sequence program, and an I10 board 1 that connects an I10R device.
d, and a communication boat 1e using the R3232C system to which a peripheral device 2 is connected, making it an -e-like PC configuration. The communication procedure with the peripheral device 2 using the communication boat 1e is performed using a dedicated command/response type procedure. In this case, the side with transmission rights sends a command message,
On the receiving side, a response message is sent in response to the command. The transmission right is transferred between the PCI and the peripheral device 2 each time a command message is transmitted. In addition, the data transmitted between the PCI and the peripheral device 2 is configured such that only alphanumeric characters other than control codes are sent using ASCII codes, and the command message sent in the above procedure is shown in Figure 2 (a). Header H, destination address AD, identification code C indicating that it is a command message, command code CC, and text data TD.
It consists of a text section TX, a check code CH, and a terminator TN. In addition, when the response message is normal, as shown in Figure 2(b), it contains a header H, a destination address AD, an identification code C that indicates that it is a response message and identifies that it is normal, and a response code. CD, a text portion TX consisting of text data TD, a tick code CH, and a terminator TN. In addition, in the case of an abnormality, as shown in Fig. 2 (C), it consists of a header H, a destination address AD, an identification code C that indicates that it is a response message and identifies that it is abnormal, and an error code ER. It consists of a text portion TX, a tick code CH, and a terminator TN. When the system is started up, the peripheral device 2, which is a dedicated peripheral device or a personal computer, has the right to transmit data. P.C.I.
Transmit to the side. This transmission is performed twice,
FIG. 3(a) shows a flowchart of the transmission. The signal transmitted here is sampled and read at intervals according to the transmission speed, so the start bit b8
A code (bo~
by) is the transmission speed of the peripheral device 2 on the sending side (for example, 960
If the transmission speed set in the communication port 1e of the PCI on the receiving side matches the transmission speed set in the communication port 1e of the PCI on the receiving side, the transmission speed shown in Fig. 4 (a>
The signal reading sampling period A on the receiving side is as shown in
corresponds to each bit of the serial signal, and the same code as the transmitted code is read. In other words, the transmission speed switching command code “9ElII,
" will be received by the PCI. By receiving this command code "9 E,...", the PCI
As shown in the flowchart of the receiving process in FIG. 3(b), the CPU 1a determines that the switching of the transmission speed matches, and performs the receiving process without switching the transmission speed of the communication boat le. Conversely, if the PCI transmission speed is set to twice the transmission speed of peripheral device 2 (19.2 Kbps),
The sampling period for reading the serial signal is shown in Figure 4 (a
), the period B is twice the sampling period A. Therefore, the code to read is “OF8.,,”OF8
゜,'', and this code “OF8゜,” is received four times in two command message transmissions, so the PCI CPU 1b receives the code “OF8゜,” as shown in Fig. 3(b).
If "F8,..." is received four times in a row, the transmission speed of peripheral device 2 becomes 1 of the transmission speed set on the PCI side.
/2, and after switching the transmission speed to the same transmission speed as the peripheral device 2 side, the reception process is performed. Also, if the reception is not received four times in a row, the process returns to the reception process. In the above case, the transmission speed on the peripheral device 2 side is 1/2 of the transmission speed on the PCI side, but conversely, the transmission speed on the peripheral device 2 side is, for example, 19.2 Kbps, and the transmission speed on the PCI side is In the case of 9600 bps, as shown in Figure 4(b), the sampling period is doubled as shown by B compared to the sampling period A when both the transmitting and receiving sides have the same transmission speed, and the transmitted transmission speed is switched. Command code “
9E tar" becomes "OF B,..." on the receiving side. Therefore, if "OF B,..." is received twice in succession on the PCI, the transmission speed of peripheral device 2 becomes PCIII.
It is determined that the transmission speed is twice that of the communication port 1e, and the transmission speed of the communication boat 1e is switched to the same transmission speed as that of the peripheral device 2 side. The received command code is 9E. , “OF8□1
, "OFB," or "□'", the received data is processed and then the process returns to the receiving process. As described above, in this embodiment, the specific transmission speed switching command code sent from the peripheral device at startup When receiving a message, the transmission speed of the peripheral device 2 is determined based on the WII of the code recognized as being received, and the transmission speed of the communication boat 1e is identified. Therefore, there is no need to operate a special switching means, and there is no possibility of switching errors. Therefore, there is no operational complexity or inconvenience.In the above embodiment, the transmission speed is determined on the receiving side by transmitting a specific transmission speed switching command code, but the R3232C control line It is also possible to switch the transmission speed using the . In other words, when connecting the R5232C using the control lines R5 and ER as shown in Figure 5, the control lines DR and ER generally have logical values "0" indicates the data set ready state and the data terminal ready state. The method of switching the transmission speed using these control lines DR and ER will be explained. First, on the peripheral device 2 side, when starting up, As shown in b), when the control line ER is changed from "0" to "1" to 0", P
On the CI side, the counter 3 of the communication boat 1e shown in FIG.
．． It is assumed that it is set to 2KbpS. After that, the peripheral device 2 side sends pulses "0"-"1"-"0" via the control line DR as shown in FIG. 6(a), and the counter 3
When the count value is increased, the frequency division ratio of the frequency divider 4 is changed according to this count value. For example, in the case of Fig. 6(a), if the frequency is divided by 4,
The transmission clock will be switched to 4800 bps. Therefore, the transmission speed in the transmission section 5 is 4800bps.
is set. Here, since the state of the control line DR=ER can generally be set by software, a predetermined transmission speed can be achieved by setting the states of the controls 11DR and ER on the peripheral device 2 side as shown in Figure 6. It is possible to switch. In addition, RD in FIG. 5 and FIG. 6 represents received data, SD represents transmitted data, C8 represents a transmission enable signal, and R3 represents transmission data.
indicates that it is a control line for sending a transmission request signal,
6 is a reference clock generating section. By the way, in the above method, the control lines DR and ER are used, but when the connection configuration of the control lines as shown in FIG. 8 is used, the transmission speed switching signal is transferred to the Pct side by using the control line R3. You may also give it to In this case, on the peripheral device 2 side, at startup, the control line R3 changes from "0 to "1" to "0" in 14 hours as shown in FIG.
”, on the PCI side, communication boat 1 shown in Figure 10
e counter 3. is cleared by the signal on the control line R3, and the outputs C0 and C3 of the counter 3 change as shown in FIG. 9, b) and c). Here, C0 becomes a clear signal for the counter 32, and C1 becomes a clock for the counter 32, so the counter 32 is cleared by the output C1, and the transmission clock output from the frequency divider 4 is set to 19.2 Kbps, for example.
shall be set to . The counter 31 indicates the specified time T4
．． A reference clock generator 6. The width T of the output clock is counted, and the output c1 is generated when T2 has elapsed, and the output C0 is generated when T has elapsed. Now, after clearing as described above, if a pulse is sent from the peripheral device 2 via the control line R8 at time T2 as shown in FIG. counter 31
However, the output C1 shown in FIG. 9(c) is generated, and this output C1 is generated.
3 causes the counter 32 to count up, and this count value changes the frequency division ratio of the frequency divider 4 that divides the clock of the reference clock generator 32.2For example, in the case of FIG. If it is 4800 bps, the transmission clock will be switched to 4800 bps. Therefore, the transmission speed in the transmission section 5 is set to 4800 bpS. Here, the state of the control line R3 can generally be set by software, so it can be controlled on the peripheral device 2 side! By setting the state of 1Rs as shown in FIG. 9, it is possible to switch to a predetermined transmission speed.

【Effect of the invention】

When transmitting data between two devices using a serial signal such as the R3232C method in a predetermined procedure, the present invention first sends a predetermined specific transmission speed switching command code to the transmitting device that has the right to transmit. If the received code read at a sampling period according to the set transmission speed of the receiving side is different from the above-mentioned specific transmission speed switching command code, the receiving side device changes the transmission speed of the sending side device based on the received code. Therefore, by sending a specific transmission speed switching command code from the sending device, the receiving device can change the reception code that has changed according to its own set transmission speed. The transmission speed of the sending device can be determined according to the content, and as a result, the transmission speed of the receiving device can be automatically switched to the same transmission speed as the sending device, and therefore connected to the programmable controller. There is no need to create a switching method each time when using a peripheral device as a dedicated peripheral device or as a personal computer, and there is no possibility of forgetting to switch or malfunction due to mistake. This has the effect of improving usability.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a programmable controller used in the method of the present invention, Figures 2 (a,) to (c) are explanatory diagrams of the format of each message used in the embodiment of the present invention, and Figure 3 (
a) and (b) are flowcharts showing the procedure for switching the transmission speed as above, Figures 4 (a) and (b) are explanatory diagrams of code reception as above, and Figure 5 is a flowchart showing the procedure for switching the transmission speed as above. 6 is a timing chart for explaining the operation of the same as above, FIG. 7 is a circuit configuration diagram of the same communication boat as above, and FIG.
A connection example diagram of the R8232C control line, which is one method of switching the transmission speed using the 8232C control line, Figure 9 is a timing chart for explaining the operation of the same as above, Figure 10 is a circuit configuration diagram of the same communication boat, FIG. 11 is an explanatory diagram of a conventional example. 1 is a programmable controller, 1e is a communication boat,
2 is a peripheral device. Agent Patent attorney Ishi 1) Chief

Claims (1)

[Claims] (1) When transmitting data between two devices using a serial signal such as the RS232C method in a prescribed procedure, the sending device that has the right to transmit first sends a predetermined specific transmission speed switching command code. transmitting, and the receiving device
If the reception code read at a sampling period according to the set transmission speed of the reception side is different from the above-mentioned specific transmission speed switching command code, the transmission speed of the transmission side device is determined based on the reception code, and the transmission speed of the transmission side device is determined based on the reception code. A transmission speed switching method characterized by switching to the transmission speed.