We are designing one multiprocessor system. There are 2 Microcontrollers. One is master which is connected to Labview Scada on RS232 on Modbus protocol. Master is connected to slave thro RS485 as the distnace between 2 systems is 500 meters. One Hand Held terminal with 20 keys & 2line x 20 char. display interface module having 8031 CPU is also connected to RS 485 network. That means Master CPU, Slave CPU & Hand held terminal CPU will be communicating over RS485 network. Also Master CPU will be communicating with SCADA over RS232 network on Modbus protocol. Which processor will be suitable for this application? How master slave communication can be achived? Please reply if you have any ready made hardware for this particular application.
Thanking you,

with best regards

Vithal Pai