RS485, can be understood as, road, MODBUS instrument can be understood as two cars. The car can run on the highway, it can also run on the country road, such as RS232, and it can also run on high speed, such as fiber optic cable. You can run on the road, horse-drawn carriage, car, ox cart (for example: MODBUS agreement, TCP agreement, or DP agreement, etc.)
What are the common protocols of PLC?
Siemens PLC
communication types:
A. MPI communication
B. Serial communication
C. PROFIBUS communication
D. Industrial Ethernet
E. ASI communication
F. PPI communication
G. Remote wireless communication
Communication protocols:
TCP, UDP, S7, profibus, pofinet, MPI , PPI, MODBUS==