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Technical Notes
RSLogix 5000 Class 1 ENBT Configuration
By Nobin William
Product: DeltaV Virtual IO Module - VIM2

This procedure describes how to configure an Implicit IO connection to an EtherNet/IP VIM2 in RSLogix 5000/Studio Designer. The procedure in RSLogix 5000/Studio Designer is the same for all VIM2 firmware options (IOD-4112: Rockwell PLC EtherNet/IP, IOD-4114: Generic Devices EtherNet/IP, and IOD-4116: ODVA EtherNet/IP) but there are differences in the VIMNet Explorer and DeltaV Explorer configuration steps.

When using Implicit IO Messaging between a Rockwell PLC to a VIM2, the PLC will act as the Scanner and the VIM2 will act as an Adapter. The PLC (scanner) will establish a connection to the VIM2 (adapter) and data between the two nodes will be exchanged at the Requested Packet Interval (RPI). Assembly Instances are used to configure what data will be written to and read. When using the Rockwell PLC EtherNet/IP VIM2 firmware, the VIM’s assembly instances are fixed, based on the serial card number and dataset number. When using the Generic Devices or ODVA EtherNet/IP firmwares, the assembly instances for the VIM are configured in the connection definition. Both scenarios will be described in more detail in the procedure.

Required DeltaV Setup (Using Rockwell PLC EtherNet/IP firmware)

1. Create a DeltaV dataset with the following settings:

Direction Output with Readback
DeltaV Data Type 16-bit UINT with Status
DeltaV Device Data Type 15
Start Address 0
Number of Values 100
Special Data 0,0,0,0,0

2. Create a second DeltaV dataset with the following settings:

Direction Output with Readback
DeltaV Data Type Floating point with Status
DeltaV Device Data Type 15
Start Address 0
Number of Values 50
Special Data 0,0,0,0,0

More details on configuring datasets using the Rockwell PLC EtherNet/IP firmware can be found here.


Required VIMNet/DeltaV Setup (Using Generic Devices/ODVA EtherNet/IP firmware)

1. Create a connection definition with the following settings:

Message Type Implicit: Class 1 IO Message → Adapter (Target Server)
Assembly Instance 1
Comm Format INT
Transfer Data 100
Maximum RPI 750

2. Create a second connection definition with the following settings:

Message Type Implicit: Class 1 IO Message → Adapter (Target Server)
Assembly Instance 2
Comm Format REAL
Transfer Data 50
Maximum RPI 750

3. Assign the connection definitions to the device in VIMNet Explorer

4. Export the VIM configuration to an FHX file

5. Import the configuration into DeltaV to generate the datasets automatically

More details on configuring connection definitions can be found here.


Configure the VIM in RSLogix 5000/Studio Designer

1. In the RSLogix 5000/Studio Designer system, right click on I/O configuration as shown below and select New Module.

I/O Configuration Context Menu - New Module

2. When New Module is selected, the following dialog will appear. Select the Ethernet Interface card appropriate for your PLC.

In this guide, we are configuring a 1756-EN2T for a ControlLogix processor. A 1756-ENBT will also work.

Select Parent Ethernet Module Type

3. Add a name and IP Address for the Ethernet card. This will be the configuration for the EN2T that is physically present in the RSLogix chassis along with the controller. The Slot number must match the slot position of the Ethernet card in the Logix chassis.

Parent Ethernet Module Properties

4. Click on the “Change” button under the Module Definition section. Select the following parameters to finish the module configuration:

Electronic Keying: Disable Keying
Rack Connection: None
Time Sync Connection: None

Module Definition Settings
Final ENET parent configuration

5. Next, right click on the ENET parent’s Ethernet node and select New Module. Then from the list provided, select and add a new 1756-ENBT module.

The VIM will be represented as this 1756-ENBT card in the RSLogix configuration. Regardless of the parent ENBT card type, this one should be a 1756-ENBT/A. Other interface card types may result in undesired behavior.

Select New Module
Select 1756-ENBT for the VIM module

6. Select a name for the VIM’s ENBT module, enter the VIM’s IP Address, and specify the Slot number as 0.

Initial Module Settings for the VIM ENBT card

7. Click “Change” under the Module Definition section. Enter the following parameters to finish the ENBT configuration:

Electronic Keying: Disable Keying
Rack Connection: None
Time Sync Connection: None
Chassis Size: 32

The PLC will not be able to properly establish a connection if the Electronic Keying, Rack Connection, and Time Sync Connection settings are not configured properly. Specifically, for example, Rack Optimization is not supported. The VIM will reject with error a Rack Optimized IO connection request from the PLC if this option is selected. Furthermore note that Rack Optimized IO connections will interfere with other, normal connections at run time, leading to unpredictable results.

The chassis size will determine how many connections the EN2T will be able to establish to the VIM2. The maximum size of 32 is recommended which allows 31 connections.

Module Definition Settings
Final VIM ENBT configuration

8. Right-click on the VIM ENBT module and select New Module. Select 1756-MODULE from the list. Configure the generic module with the settings in the following screenshot.

Select New Module
Select 1756-MODULE
Generic Module Configuration

If using the Rockwell PLC EtherNet/IP VIM2 driver, the module as shown will generate tags to be used with the first output with readback dataset on the first serial card. In the Assembly Instance column, the Input and Output parameters are the dataset index numbers. In this example, these are specified as 1 for the first dataset on Card 57. The valid range for these parameters is 1-128. This parameter is calculated based on the target card/dataset to which the ENBT is mapped. The following table can be used as a quick reference.

Assembly Instance Mapping for the Rockwell PLC EtherNet/IP VIM2 Firmware

Serial Card Serial Card Calculated Assembly Instance Range
57 61 1-32
58 62 33-64
59 63 65-96
60 64 97-128

Examples:

To map an ENBT module to Card 57, Port 2, Dataset 1, use an instance parameter of 17.

To map an ENBT module to Card 59, Port 1, Dataset 5, use an instance parameter of 69.

The ODVA and Generic Devices EtherNet/IP VIM2 drivers do not follow this assembly instance mapping. Instead, these firmware options use connection definitions which define assembly instances for the given datasets. The valid range is still 1-128. The Assembly Instances in the generic module configuration will need to match the assembly instance defined in the connection definition. In this example, this generic module will generate tags to be used for the connection definition that uses Assembly Instance 1.

The Input and Output Size Parameters should match the number of values in the DeltaV dataset. Lastly, specify the Comm Format. The Comm format corresponds to the DeltaV data type. For example, INT corresponds to 16-bit unsigned int.

Do not use any data type other than an array of a basic type.

The VIM does not support user-defined data types.

9. After finishing the generic module configuration, update the RPI under the Module Properties → Connection Tab to a value between 200 – 750 ms. This will specify how often data is exchanged between the PLC and the VIM for this module. For few (less than 8) datasets, an RPI of 200ms may be used. For more than 16 datasets, the RPI may have to be adjusted up to the maximum (slowest) rate of 750ms.

Configuring an RPI of less than 100ms is not recommended. The VIM will not be able to keep up with messages from Logix, causing datasets to have bad status.

Unicast connections are recommended. Select the Unicast Connection over EtherNet/IP checkbox. The PLC will use Multicast messages when this option is not selected. However, the VIM will support either method.

RPI Settings

10. Create the 1756-MODULE for the second DeltaV Dataset

Select New Module
Select 1756-ENBT
Configure the Generic Module
Configure RPI Settings

Note that this module is configured for DeltaV dataset 2, and has a Comm Format of REAL. This corresponds to a DeltaV dataset of type floating point, with a maximum of 50 registers.

11. The final configuration with 2 connections will appear as follows:

Final RSLogix/Studio 5000 IO Configuration for a ControlLogix Processor

12. The generic module tags should be available under the Controller Tags node.

Controller Tags

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Emerson Automation Solutions
Process Simulation Center of Excellence
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