Figure 5: Select the Connection Definition
This application note describes the recommended settings for integrating the PowerFlex 755 AC Drives using Ethernet/IP Class 1 messaging with the Generic Ethernet/IP Virtual IO Module (VIM).
This article describes the PowerFlex 755 Connection Definition that is included with VIMNet Explorer v188.8.131.52 and later. This connection definition allows the Generic VIM to quickly establish communication with the PowerFlex 755 in default mode without the need to configure the connection manually. The first half the article walks through the how to import the connection definition into the VIMNet Explorer project and add the connection to the device. The second half of this article explains the connection parameters in greater detail.
Import the Connection Definition:
To import the connection definition and add it to a device, follow the steps illustrated in Figures 2-6.
Adding the PowerFlex 755 connection will result in two datasets for the Drive. Expand the connection to view each dataset. Click "DS01" to view the DeltaV dataset configuration on the right-hand side. The DeltaV dataset needs to be configured exactly as shown. The default connection definition will use the settings shown in Figures 12 and 13. Altering the dataset to include the datalinks will result in a different dataset configuration.
Upload the configuration to the VIM after adding the connection to the device and the VIM will be ready to communicate to the PowerFlex 755.
Class 1 Connection Settings and I/O Mapping:
There are several factors that separate the PowerFlex 755 from the PowerFlex 70/700-Series:
Even though the PowerFlex 20-COMM-E is not required for Class 1 communication to the PowerFlex 755, the Class 1 assembly instances and I/O mapping can be found in the user manual. Figures 2-4 were pulled from the 20-COMM-E User Manual.
The Assembly Instances in Figure 2 were used for the Connection Definition and are utilized in the Message Parameter settings. These Assembly Instances are the same for every PowerFlex Drive.
Figure 3 shows the I/O Mapping scheme for the PowerFlex 755 Drives. The 755 utilizes 32-bit Reference and Feedback but the table uses 16-bit words. For instance, Logic Command under the Output I/O actually occupies words 0 and 1. The same goes for the Logic Status in the Input I/O Table.
The Pad Words contain no data and the PowerFlex_755 connection definition excludes these words from the input dataset.
Figure 4 is a handy self-check, as it shows the Input and Output sizes juxtaposed with the user-defined drive configuration. The high-lited row is the default setting and was used for the connection definition.
Connection Definition Settings:
To view or edit the connection definiton, right-click the definiton and select "Properties." Note that the configuration does not need to be edited to work with the default PowerFlex 755 configuration.
Figure 9 shows the default Connection Definition settings for the PowerFlex 755.
Selecting Element 2 of the Input Buffer Definition, clicking "Edit," and then clicking the "Fields" button will result in the window shown in Figure 10. This window shows an explaination of which values occupy the registers. The offset is in bytes rather than registers. The Fields configuration has no impact on the communication and the only purpose is for extra clarification.
The PowerFlex 755 data uses the DINT or 32-bit format. DeltaV only supports INT (16-bit) or Floating point but not DINT. This compatability issue was addressed by splitting the data into 16-bit registers. The first half of the 32-bit word, the Least Significant Word (LSW), is located in the first register. The second half of the 32-bit word, the Most Significant Word (MSW), is located in the second register.
The two 16-bit Pad Words were seperated from the Logic Status and Feedback and are marked as unmapped bytes. This means that these empty registers will not exist in the DeltaV Dataset. The first register of the input dataset will be the Least Significant Word of the Logic Status.
The Fields can also be viewed for the Output Buffer as shown in Figure 11.
As shown in Figure 12, the Assembly Instances and Data Sizes are configured in the Class 1 Message Parameters. Note that the Data Size is in bytes rather that 16-bit words which is why the values are twice what is shown in Figure 4.
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