Technically, there is no limitation on the number of MAX3322E transceivers on RS232 bus in multidrop application. Users just need to make sure three things
1. There is no more than one transmitter driving the bus at one time.
2. There is only one receiver one the bus that has 5KΩ input resistance. Other receivers are high input impedance. Or if the users do not want to control the input impedance of the receivers, they can set all the receivers to high input impedance and place a 5KΩ termination resistor that connects the bus and ground.
The purpose is to keep the equivalent load on the bus around 5KΩ to comply with RS-232 standard.
3. More peripherals and longer cable mean more load capacitance. This can degrade the signal slew rate. The capacitance of the bus is heavily depending on cable length . So, the users have to make sure that the signal slew rate still meet the specifications.