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