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| Author | Topic |
| zellhwang Tl Posts: 5 Singapore | Posted - 8/1/2004 7:54:46 PM    Hello, I'm not sure whether this can be done. I would like to send some FSK signals to a dumb terminal which does not perform handshaking. Is it possible to set the modem into data mode after dialing up (using ADTDXXXX) or simulate handshaking so that I can send FSK signals (v.23) after my call is picked up ? Thanks & rgds |
| v.Richard Tl Posts: 6222 USA | Posted - 8/5/2004 9:30:52 PM  It depends upon the modem - some modems will support V.23 - many modems support the command AT+MS=? which will display list of protocols you can use with the command. Aloha! Richard. |
| zellhwang Tl Posts: 5 Singapore | Posted - 8/7/2004 10:21:54 PM Hi Richard, thanks for your reply! .. ;) Yes, I know that some modems support v.23 and you can set them to that mode of modulation us AT Commands. However, all that I've come across require handshaking/negotiation, before they enter 'transfer mode', which allows sending of FSK data (in v.23 mode). I'm actually looking for modems which does not require handshaking and can receive or send FSK signals at 1200bps.... |
| charles Tl Posts: 5879 USA | Posted - 8/7/2004 11:22:41 PM If all you want is a connection, no actual handshake, and simple data stream sent via software, use "ATD;" as the last portion of the init string. This will simply set the modem in a command mode. You may have to manually issue the send data command after that. |
| zellhwang Tl Posts: 5 Singapore | Posted - 8/8/2004 10:31:40 PM Hi Charles, thanks for your reply ... :) Yes, I understand that you can drop to command mode by add the ";". However, I don't know how I can "manually issue send data command". I have a some binary string ( formed by hexadecimal), which I would like to send, but I can't find any AT command to manually send data. Please enlighten. Thanks & Rgds |
| v.Richard Tl Posts: 6222 USA | Posted - 8/8/2004 11:54:11 PM I don't think you can do this without a handshake - the V.23 standard is an asymetrical 1200bps w/ a 75bps backchannel. While V.23 modulation is FSK that won't make it compatible with a device that doesn't use the V.23 protocol. That said - the command I suppose you've seen this? Aloha! Richard. |
| zellhwang Tl Posts: 5 Singapore | Posted - 8/9/2004 2:24:00 AM Richard: Yes, I've saw that thread before. However, it was opened ended too. Yes, I understand that handshaking is required for modems in order to determine the modulation to use. I suppose its something to do with the firmware. The once the connection is established, the modem will switch to "transfer mode", which allows transferring of data. I'm just wondering whether I can fix the modulation without handshaking and trigger "transfer mode" somehow ... |
| charles Tl Posts: 5879 USA | Posted - 8/9/2004 11:03:08 AM Might get in on this . http://www.experts-exchange.com/Hardware/Modems/Q_21075724.html I wonder if this could be done with a modem script or might look at this. Were is the dumb terminal. |
| zellhwang Tl Posts: 5 Singapore | Posted - 8/10/2004 12:01:49 AM Charles: Thanks for the thread. Seems like it is opened ended too. I've looked at the document that you provided on setting up the modem for leased line operation. The configuration seems to make the modem 'auto-connect', as such the connection is established by the modems automatically. I assume that handshaking still occurs there. I've actually looked through the AT Commands for my modem. Sad to say, I can't find any commands that allows me to send data, other than to create DTMF Tones. :(
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