hi V. I'm sorry keeping on bothering you. I agree with you, it is ok to load the whole data to memory. But I need to write data back and close the file at every editchange, because the file will be accessed by another class. Fortunately, I have only 8 data need to handle, the speed is compltely fine with me. My tesk is like this: I use MFC to make a dialog. I have serveral tabs with about 8 spins on each of them. and I add these tabs on a base dailog. I send the spin value out on a master query(I'm slave on the bus. I cann't send data out on my own. I need to wait the query command.) So I decide to store the tabs spin values in several files(every tab has it's own file), and open a serial port on the base port. When the user change the spin value, he only change the file, but doesn't send it out. When the master polling, I send the file data to master.(the polling speed is faster than the user's finger to click spin, of course) Will my idea work? One more ask V. wrote: "#value1|value2|...|valuen#" if I make my file like this: 10 15 20 when I fread them, CString will treat 10 to be one byte, or treat 1 as one byte and 0 as teh second byte? Many thanks for your help beforehan. slow-witted chauteen

Thanks for your reply first. For I am trying your way, to read the entire file and then write the whole data back.(the work I want to do is store 8 spin vlaue to a file, and update when the user click and change spin value.) but I use a brute force way, for I don't know how to read data in CString:confused: I declare an BYTE array, called buffer[8], and in the dialog's init, I read in the file fread( buffer, sizeof( BYTE ), 8, filespin ); and in the spin message, I add fseek(filespin, 0, SEEK_SET); fprintf( filespin, "%s", buffer ); I've also tried fwrite fwrite( buffer, sizeof( BYTE ), 8, filespin ); both failed the output file will contain some strange code, like slash , camma or something. I try to show the readin buffer text on a editbox, and it already contain a unexpected slash and the end.:confused: It seems the read in have something wrong already, not to mention write data back. Can you suggest me some smart or "correct" way to do? Thank you very much. chauteen

hi, Can you say something more about fseek please? how to use fseek to go to a certain line of a file. For examlpe, I need to overwrite the thrid line of the file. But fseek and fgetpos simply moving the file pointer in the same line, not be able to next line. Thankx. chauteen

It's me again. I'm still fighting with tabs. I have 7 tabs with spins on them, and one Dialog. I use Propertypage, and use the instruction "AddPage" to make the 7 tabs on the dialog. Now I want to store the spin value in a flie when the user click and change the spin value. (or maybe in 7 different file, for one tab own one file belong to itself) Then, I have to communicate with a controller throu RS-232 under modbus portocol. Because I'm slave on modbus, I only can send data out when the controller send out query message. So I planning to store the spin value in files, then waiting untill the query message, then I send the data I stored in the file. I would like to ask how to deal with the file pointer. I use the code: in my base dialog' cpp: FILE *filedlg; filelog = fopen( "file_page1.txt", "r+" ) What code about pointer assignment I suppose to write in tab page1' cpp or h file to complete the rest? I mean page1 doesn't know the exitance of file pointer filedlg. I'm new about pointer and MFC, and would be many appriciate about your help. chauteen

I'm writing a dialog by MFC. I need to send data out through RS-232, using Modbus protocol. I know there are many classed written for serial communication, but not for Modbus. Does anyone have already fought with modbus and survied? Please give me sone advice. Thanks. chauteen

Hi, I'm writing a dialog by MFC. I have several tabs, and every tab has some control items on it. I creat classes for every tab. I want to send out status thru RS-232, such as when the user click one spin, and the spin value will be sent out thru RS-232. My problem is I've got the tab class and a serial class ready. But how to confige a serial port that can be used by "all" tabs. If I create the port in one tab's cpp, other tabs will not be able to use the port, of course. However, it doesn't work if I configure a port in the project's main cpp, either. Forthermore, if I call the functions in the CSerailPort class, like: CSerialPort::Openport("com4"); The compiler says another error: illegal call of non-static member function. Thanx your help. Chauteen