Post by thread:ZModem [OT sort of]

Anyone familar with ZModem? Here is my situation. I am sending data from a uC via a serial port to a PC. On the PC, I have Hyperterminal running in capture mode. I have the baud rate set at 57.6kbps 8-N-1 and hardware flow control. I am properly taking care of the hardware flow control lines CTS,RTS,DTR and DSR by looping them back to each other. I can transmit my data which is HEX and comes out as ASCII characters on the Hyperterminal window just fine; however what I really want to do is to use the "Receive File" mode instead of the "Capture Mode" because I want my data to be automatically saved as a file. As opposed to just sitting in the Hyperterminal window. When I start the "Receive File" mode in Hyperterminal it asks me for the protocol...XModem, Kermit, ZModem etc. I have heard that ZModem is the best but I would be willing to use any one of them if I could just get the PC to start receiving my data using one of these protocols ("Receive File mode"). What happens is that it times-out like it is waiting for a special byte or a header before the data. It never starts receiving. Does anyone know what I need to send the PC in order for it to start receiving my data using ZModem? Perhaps it is a special header or couple of bytes preceding the data that will start it. Again, the serial port is configured for 57.6kbps 8-N-1 and hardware flow control and I am using the same hardware flow-control loopback trick that I used successfully with the "Capture mode". Any Hints, Suggestion, or Clues. The next thing I am going to try is to send a file with just one ASCII character from one PC to another using a null modem and this "Receive mode" using ZModem and probe the data that gets sent. Thanks, uC_Novice __________________________________________________ Do You Yahoo!? Send instant messages & get email alerts with Yahoo! Messenger. http://im.yahoo.com/

Xmodem is the simplist of the hyperterm-compatible file upload protocol. For Xmodem, divide your data into block of 128 bytes each. For each block send SOH <blknum> <NOT blknum> <checksum> Wait for an ACK to be received before sending the next block, resend the block if you get a NAK. Terminate the file by sending just an EOF instead of a new block. Ymodem adds some filename control and upgrades the checksum to a CRC, and some versions allow for a larger blocksize. Zmodem adds sliding windows for full bandwidth utilization. Basic source code implementing Xmodem sent under separate cover... BillW

In message <spam_OUT20000515054355.24276.qmailTakeThisOuTweb4703.mail.yahoo.com>, uC Novice <.....uc_newbieKILLspam@spam@YAHOO.COM> writes >Does anyone know what I need to send the PC in order >for it to start receiving my data using ZModem? >Perhaps it is a special header or couple of bytes >preceding the data that will start it. Again, the >serial port is configured for 57.6kbps 8-N-1 and >hardware flow control and I am using the same hardware >flow-control loopback trick that I used successfully >with the "Capture mode". X-Modem, Z-Modem etc. are packet systems, they send data in packets of a certain size, X-Modem uses 256 byte packets, and Z-Modem uses 1K packets, although I seem to recall it can use different sizes?. X-Modem is quite simple to implement, but Z-Modem is somewhat more difficult, but in either case I don't think it's what you really need to do. It would be much easier to write a comms program on the PC to just save the incoming serial data straight to disk, there's no need to get involved in complicated packet systems. -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : nigelgKILLspamlpilsley.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.co.uk | | Chesterfield | Official site for Shin Ki and New Spirit | | England | Ju Jitsu | \--------------------------------------------------------------/

In-Reply-To: <.....kKh3hjAs05H5EwxvKILLspam.....lpilsley.demon.co.uk> Nigel Goodwin <EraseMEnigelgspam_OUTTakeThisOuTLPILSLEY.CO.UK> wrote: > X-Modem uses 256 byte packets No, X-Modem uses 128 byte packets except the X-modem-1K variation which (obviously) uses 1K packets. > and Z-Modem uses 1K Z-modem doesn't really use any particular size, a particular implementation of Z-modem may use a particular size or it may adjust the size according to how many transmission errors occur. X-modem is indeed fairly easy to implement. I think I have a file about it somewhere I could email to uC Novice if required. Brian Gregory. briangspam_OUTcix.co.uk