Can you help me to understand the difference between following communication protocol?Controlnet/Devicenet/Ethernet?


#1

Controlnet/Devicenet/Ethernet??? What is the difference?


#2

ControlNet:
Was primary designed for communications between PLCs, especially applied with Allen Bradley PLCs and Remote I/O (FlexI/O), it has an advanced algorithm based on time slices to ensure the reception of messages. It is called CIP or Control Information Protocol, the maximum speed is 5MB/s. This protocol is regulated by ODVA (Open Devicenet Vendor Association)

DeviceNet:
This protocol took the algorithm of Controlnet and applied to primary use interconnecting Intelligent Motor Drives with another Drives or with PLCs. The algorithm ensure proper communication. (ruled by ODVA)

Ethernet:
It uses a probabilistic method to communicate (CSMA/CD), the key question is CD that means Collision Detection, in other words, they detect collision and re-transmit the message at high speed (max speed 1000MB/s)

Ethernet/IP
IP=Industrial Protocol (please don’t confuse with Internet Protocol as TCP/IP):
They uses exactly the same CIP algorithm than ControlNet and Device, that means is deterministic, sharing the time to guarantee the delivery of messages. It is completely approved for control but you can not mix Ethernet/IP devices with non-Ethernet/IP, because the last will not respect the time assigned. Ethernet/IP was designed by Rockwell Automation but they open for free to any provider and gave the control to the ODVA


#3