Testing the Raspberry Pi with:

• ArchLinux and Proview 4.8.5-1 (Development Station)
• 2 x Arduino UNO (serial) baudrate 38400 (34 I/O's)
• 1 x Arduino UNO with Ethernet shield (LAN), configured as Modbus-Slave (5 x Ai, 1 x Di, 1 x Do). Proview as Modbus-Master.
  
• PLC scan time 100 ms, rock solid.
• 40% CPU, without graphs and only signal handling, Proview eats 6% CPU