RS-232 to Multiple Destinations

[SailorMan]

I have an application where we would like a single RS-232 data stream to be made available to two destinations. I fully understand that RS-232 is point-to-point communications (not multi-drop) but in this case the destinations are specified as 100% read-only ports. I have seen other working applications where the Tx (from the souurce) was sent to two Rx ports, the Rx (from the source) to two Tx ports and of course the signal ground (from the source) to both. This was done without a signal converter / amplifier. I should have mentioned that we are not using any handshaking protocols - only Tx, Rx and Sig Gnd (2, 3, 5).

Has anyone completed such an installation? It does not seem like a recommended practice but $ is always the issue!

I appreciate any comments.

 

[cbarn24050]

Hi, there is no reason why you can't do that as long as you dont overload the transmitter. The problem is that you cannot verify that the data has been recieved properly.

 

[JayAnthony]

The method that you describe was exactly the way manufacturers did multidrop before tristate RS422/485 was invented. The firmware of the node, though, was responsible for the re-transmission of the signal.
As long as your remote nodes are "listen" only, you should be able to get by with up to four nodes if you keep your distance short and your impedance high.

 

[tomatge]

Assuming that you are looking for an "off-the shelf" solution, I think the device you are looking for is called a modem splitter or modem sharer.

They are available from Black Box or Westermo. The Westermo device allows you to configure priorities on the ports etc. which in some applications may be useful.