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The task is to establish data exchange between 2 PLCs.

There are 2 main ways to exchange data: NVL and Modbus TCP.

Below are tables of advantages and disadvantages of these two methods, however, the biggest difference lies in which data transmission protocol is used.

TCP vs UDP: Differences between the protocols. The main difference between TCP (transmission control protocol) and UDP (user datagram protocol) is that TCP is a connection-based protocol and UDP is connectionless. While TCP is more reliable, it transfers data more slowly. UDP is less reliable but works more quickly.

NVL or Network Variables List

https://help.codesys.com/api-content/2/codesys/3.5.13.0/en/_cds_f_networkvariables/

Advantages	Disadvantages
Easy to use	Uses UDP protocol, UDP provides a simpler and less reliable form of data transmission
Data transmission efficiency: NVL sends data in packets	Delivery is not guaranteed
Absence of a main node: NVL does not have a binding to a main or subordinate node, making it more flexible in usage and management	Only UDP protocol or it's limited protocol support
	Optional data reading: Since data can be available to all nodes, there is no guarantee that all nodes will read or use this data

Modbus TCP

Advantages	Disadvantages
Reliability: Modbus TCP protocol ensures reliable data transmission with acknowledgment of receipt	Use of master and slave in data transmission
Wide support	Limited data transmission speed: More complex data transmission protocol.
Delivery is guaranteed

Since we are simulating the use of a bridge panel, we need to use TCP protocol for reliable data transmission.

PLC1 is 158.38.140.56. It will be a master.

PLC2 is 158.38.140.57. It will be a slave.

According to the task we need to transmit data of INT and BOOL types.

Source:/Helpful links:

Configuring a Network Variable Exchange:
https://help.codesys.com/api-content/2/codesys/3.5.13.0/en/_cds_configuring_network_variables_exchange/

Modbus TCP:

https://www.prosoft-technology.com/kb/assets/intro_modbustcp.pdf

https://www.avast.com/c-tcp-vs-udp-difference#:~:text=TCP%20vs%20UDP%3A%20Differences%20between%20the%20protocols,reliable%20but%20works%20more%20quickly.