Modem/Modem connection (AGAIN)
I was just browsing through some modem problems and I was surprised by some people's statement that you can connect modems without a line/line simulator.
I know how to deal with serial connections, but I have a similar problem that I have to connect two modems. Usually there will be a real phone line in between, but there are cases when I don't have that line. Until now I thought I'd have to buy one of those (expensive) line simulators, but now it seems I should be able to handle it with s/w only.
So here is my question: Is it really possible to communicate modem to modem without telephone hardware in between? What cable do I use (crossed over phone cable?)? What do I have to do on the s/w side (I saw a AT command there ...)?
Please do not start the discussion again IF it's possible, only comments HOW to do it! Trust me, I never thought it would be possible.
I know how to deal with serial connections, but I have a similar problem that I have to connect two modems. Usually there will be a real phone line in between, but there are cases when I don't have that line. Until now I thought I'd have to buy one of those (expensive) line simulators, but now it seems I should be able to handle it with s/w only.
So here is my question: Is it really possible to communicate modem to modem without telephone hardware in between? What cable do I use (crossed over phone cable?)? What do I have to do on the s/w side (I saw a AT command there ...)?
Please do not start the discussion again IF it's possible, only comments HOW to do it! Trust me, I never thought it would be possible.
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Also, If you wanted to run a phone line a very long distance, you could also supply your own talk battery if you wanted to use telephones. Modems supply a carrier where phones have no way to supply power on their own in any amount.
For Joe : is this going to work ? i believe one modem should be in answer mode, and the other one in originate mode.
For a modem to start in originate mode, you will have to issue AT command to stop the dialtone detection.
For a modem to start in originate mode, you will have to issue AT command to stop the dialtone detection.
As far as I recall we havn't had to worry about about originate/answer since the days of 300 baud - remember that?
Why would you use a modem to modem link to connect PC in the same room. A null modem cable would do just fine and run at 115,000 baud. Procomm can handle a direct connect type link and so can most other things.
Modem to modem is really only required if you are driving over a substantial distance. A made up or $5 null modem plug will get you within most poffices or factory complexes.
Why would you use a modem to modem link to connect PC in the same room. A null modem cable would do just fine and run at 115,000 baud. Procomm can handle a direct connect type link and so can most other things.
Modem to modem is really only required if you are driving over a substantial distance. A made up or $5 null modem plug will get you within most poffices or factory complexes.
ASKER
Thanks a lot Joe, that's what I needed! The first time somebody made a clear statement in this discussion. I haven't had a chance to try it yet, but this weekend I'll give it a shot.
A comment for colinmiller:
Imagine you are designing a hardware that has the modem chipset on board, is supposed to work over modem(with phone line), but should also work in a closed enviroment like a building (where you don't have a telephone system). If you can do the direct connection, you can deal with the whole thing from the s/w side instead of having different h/w designs.
A comment for colinmiller:
Imagine you are designing a hardware that has the modem chipset on board, is supposed to work over modem(with phone line), but should also work in a closed enviroment like a building (where you don't have a telephone system). If you can do the direct connection, you can deal with the whole thing from the s/w side instead of having different h/w designs.