PLC to PLC communication
Consumed and Produced tags
This type of communication is used for PLC – PLC communication. Data is exchanged in real-time between the two controllers. The data exchange takes place via the so-called Consumed and Produced tags. Tag stands for a variable name. The Consumed tag receives the data. The Produced tag provides the data. This means that a Produced tag is created on one controller first, the opposite side that is supposed to receive the data "consumes" the data, hence Consumed tag. This type of communication always requires two EtherNet/IP scanners.
In the following paragraph this is explained by means of a TC3 controller (CX2020 in this case) with the function EtherNet/IP Scanner TF6281 and an Allen-Bradley CompactLogix from Rockwell (RSLogix5000 V20.03.00).
Both sides are described here to set up a communication as described above.
TwinCAT 3.1 Build 4022.x
ProduceTag in TwinCAT
First, the EtherNet/IP scanner is created in TwinCAT (IP address and further settings can be found in the previous chapter Settings dialog ). Right-clicking on the EtherNet/IP Scanner opens a dialog. Select Add New Item….
Then select Producer Object List:
A Producer Object List is then created below the scanner. This is available only once, even if the data is sent to more than one controller. Right-click on Producer Object List and select Append Producer Connection.
Now specify the name of the Connection Tag. This must be identical to the name of the consumer.
Then define the number and type of data. It is only possible to use DINT or larger variables.
For the further steps, the name TwinCAT_IN_0 and a variable of type DINT were selected. To do this, navigate to the outputs of the Producer Object and insert a variable of type DINT.
Set the Transport Trigger to Cyclic. Other operation modes are currently not supported.
Consumer Tag in TwinCAT
Next, create a Consumer Tag. To do this, create a Generic EtherNet/IP Slave in the EtherNet/IP Scanner. It requires the IP address of the Allen-Breadley CPU. Enter the address and add an Append Consumer Connection Consumer tag under the newly created slave. The name is important because it must later be specified as a Produced variable in the Allen-Breadley CPU.
The Port is the CPU port on which the variable will be used later. Usually this is 1.
Now you have created a producer in the TwinCAT tree and a consumer for the other EtherNet/IP controller.
