Multi drop RS232 network

[elexlearner]

rs232 multidrop

Hi,

I want to connect the three devices such that PC and D1; also D1 and D2 can communicate on RS232 level.

I have a problem in connecting the 3 devices. It works fine between D1 and D2 but whenever there is transmission by PC the D2 loads the line.D2 has RS232 to TTL converter (MAX202).

What can I do .

 

[IanP]

multidrop rs232

In the RS-232-multidrop application you can't use standard RS-232 drivers such as MAX232 or MAX202 ..
The only option is to employ drivers with tri-state outputs ..
As an example, have a look at the MAX250 ..
**broken link removed**

Rgds,
IanP

 

[elexlearner]

rs232 network

Thanks!!!
IanP

But what do u think about this ...
**broken link removed**

I am using the same..

Regards,

 

[IanP]

multi drop rs232

MAX3322 should also work fine as it has the [Tx Enable] pin ..

You have to arrange this 3-device-network in a similar way as all other networks work, that is, each device has it’s unique address, for example 01, 02, and so on, and the string that is used consists of address followed by data ..

The idea is not to have more than one transmitter enabled at a time, but all devices have to be enabled to “listen” and become active only when asked to ..

Rgds,
IanP