With Windows popularization in China, especially Windows 95, more and more microcomputer users turn to the Windows operating system. However, the development of Windows applications is not easy to do with technical personnel in general engineering technicians, but not only Windows's message circulation mechanism is not easy to understand, but also develop a function of strong, beautiful applications, and its programming and debugging workload is very huge. Many engineers who do not engage in software are daunting for Windows programming. However, using Microsoft's VisualBasic to develop these aspects of Windows applications are very convenient, and general engineers are easy to master, the design software interface is very convenient, programming workload is relatively small, only programming and small interface control of primary application functions Program. This article describes some gains that the author uses VB in serial communication programming. Due to the introduction of the serial communication programming in the newspapers and magazines, the introduction of Microsoft C or Borlandc is used, so the author is willing to discuss the application of VB in this area. . The development of computer measuring system software for serial communication using the RS-232 interface has a certain reference value.
In this system, an 80C31 single-chip microcomputer is used as a low-bit machine to collect the inertial sensitive components. The data is transmitted to the upper PC through the RS-232 serial port after a certain pre-treatment. Run the detection software in the Windows environment on the PC, accept data from the serial port, perform data processing, display, storage, etc. The data processing results are printed in the form of table.
In VB3.0, there are many professional manufacturers to provide user-customized controls, which are .vbx suffix, where Mscomm.vbx is a control for serial communication. For VB3.0, the control is included in the control toolbox (Toolbox), otherwise the control can be added to the control toolbox with File | AddFile. Then you can use the control for serial communication.
Here, a simple example will illustrate how to perform serial communication programming, which uses VB3.0 with VB3.0 in a Windows 95 environment:
1. Create a project file first, its control is as follows:
2. The code is as follows:
Subform_load ()
Comm1.commport = 1 'uses serial port 1
'Baud rate 9600, doll verification, 8 data bits, 1 stop bit.
Comm1.settings = "9600, e, 8, 1"
When using Comm1.input, take one byte each time you use the receive buffer.
Comm1.inputlen = 1
The interrupt interval of the Timer1.Iterval = 20 'timer is 20ms for updating the display time.
EndSub
Subcmdcomm_click ()
DIMECHOCH% 'Command variable
StaticMaxF01 &, Maxf02 &, Minf01 &, Minf02 & 'maximum, minimum
OnErrorResumenext 'simple error handling
MAXF01 & = Maxf02 & = 0 'initialization variable
Minf01 & = 32767
Minf02 & = 32767
Label2.caption = Comm1.Settings' Displays the settings of the serial port.
Ifcmdcomm.caption = "Communication" THEN 'If the prompt of the current command button is "communication", start sending and
cmdcomm.caption = "Stop" "accepts data, and change the command button to" stop "
cmdexit.enabled = false 'Allows to stop communication. The exit command has failed in communication.
IfNotcomm1.Portopenthen 'is not open if the serial port is not open, turn on the serial port comm1.portopen = true
ENDIF
IFcomm1.Portopenthen
Ifcho.text <> "" "If the command input box is not available, turn it into a hexadecimal value
Echoch% = VAL ("& H" echo.text)
Else
Echoch% = & HF0 'Otherwise, the provincial command is F0H
ENDIF
Comm1.output = chr (echoch%) 'writes a byte command to the serial port, by Windows
Endif 'moved the command
Label3.caption = hex (echoch%) 'Shows the command just issued
DowhileComm1.Portopen
Ifcomm1.inbuffercount> 0then 'If comm1.inbuffercount> 0 indicates a buffer
CH $ = Comm1.input 'has data and reads a character,
If the IFASC (CH $) = echoch% Then 'is the same as the issued command, then exits the current loop
EXITDO 'enters the next loop
ENDIF
Else
Comm1.output = chr (echoch%) 'Otherwise, continue to order to the next machine, notify the next machine
ENDIF 'Sending Data
Dummy = doevents () "Let the system handle other messages
Loop
'The lower machine accepts the correct command, and the return command is correct, go to the following cycle
i = 1
DowhileComm1.Portopen
IFcomm1.inbuffercount> 5then
CH $ = comm1.input
DowhileASC (CH $) <> echoch% 'Test data in command byte
CH $ = comm1.input
Loop
CH1 $ = Comm1.input 'Accept buffer reading test data from Windows serial data
CH2 $ = comm1.input
CH3 $ = comm1.input
CH4 $ = comm1.input
NEWF01 & = ClNG (CLNG (ASC (CH2 $) * 16 * 16 ASC (CH1 $)) 'merged into an integer
NEWF02 & = ClNG (ClNG (ASC (CH4 $) * 16 * 16 ASC (CH3 $))
IfNewF01 &> Maxf01 & kiln 'judgment maximum, minimum
MAXF01 & = Newf01 &
ENDIF
IFNewF01 & Minf01 & = newf01 & ENDIF IFNewF02 &> Maxf02 & Ten MAXF02 & = Newf02 & ENDIF IFNewF02 & Minf02 & = newf02 & ENDIF Labf01.caption = Str (newf01 &) 'Display data Labf02.caption = STR (NewF02 &) Labmaxf01.caption = STR (MAXF01 &) Labminf01.caption = STR (Minf01 &) Labmaxf02.caption = STR (MAXF02 &) Labminf02.caption = STR (Minf02 &) Else Comm1.output = chr (echoch%) ENDIF Dummy = doevents () loop Else 'During the communication process, press the CMDCOMM button to stop communication and stop testing CMDComm.caption = "Communication" command, turn off the serial port, make the exit button valid. Comm1.output = chr (& H5f) Comm1.portopen = false cmdexit.enabled = true ENDIF EndSub SUBCMDEXIT_CLICK () Ifcomm1.portopenthen 'confirms close serial port Comm1.portopen = false ENDIF End 'termination of the entire program EndSub Subtimer1_timer () 'Update Display Time Iflabtime.caption <> Time & Then Labtime.caption = Time $ ENDIF EndSub 3. Program instructions: a. The communication protocol of the above program is: the baud rate 9600, even check, 8 data bits, 1 stop bit. The start test command is sent by the host computer, and the detected data is transmitted to the upper machine every 500 ms after receiving the command. Each time you send 5 bytes, the first byte is the command accepted by the next machine, the value of the second three bytes of 16Byte, the value of the fourth-fifth byte is 16byte. The upper computer is recycled and processed and displayed data; b. Due to the data transmitted and accepted by the serial communication, the data transmitted and accepted is more than hexadecimal, so the number of hexadecimal numbers in the program, in the program via echoch% = Val ("& H" Echo. Text) Convert the entered echo.text to a hexadecimal number and assign the variable echoch%. When the serial port is sent, Comm1.output requires accepting character type variables, so it is achieved by statement comm1.output = chr (echoch%); c. When you accept data, each time you want to judge whether the first byte is a command, only the 4 bytes of the following are the correct data, otherwise check the next byte. Implementing a byte from accepting buffer from accepting buffer by setting Comm1.inputlen = 1; d. When exiting the program, be sure to turn off the serial port and complete it through the comm1.portopen = false; e. If you need the upper machine to query the lower machine, serial communication can be performed in the timer Timer1-Timer event; f. To achieve a complete function, we must further improve the program, even to use WindowsAPI, OLE, etc., the above procedure is just a simple example; The author introduces the author's harvest in the use of VB development Windows environment, the author develops an interface-friendly, comprehensive and convenient satellite control system inertial sensitive component detection software using the above principles. The actual use effect is good, improved work. Efficiency, and even automation of testing and data processing.
