Overview

The following unconnected explicit messaging example shows you how to use the MBP_MSTR function block to retrieve diagnostic information for an STB island from an STB NIC 2212 network interface module, by using the Get_Attributes_Single service.

You can perform the same explicit messaging service using the EtherNet/IP Explicit Message Window of the Control Expert Ethernet Configuration Tool.

Implementing the MBP_MSTR Function Block

To implement the MBP_MSTR function block, you need to create and assign variables, then connect it to an AND block. In the following example, the logic will continuously send an explicit message upon receiving notice of success:

Input Variables

Variables need to be created and assigned to input pins. For the purpose of this example, variables have been created — and named — as described below. (You can use different variable names in your explicit messaging configurations.)

Output Variables

Variables also need to be created and assigned to output pins. (The names assigned to output variables apply only to this example, and can be changed in your explicit messaging configurations.)

Control Array

The control array parameter (EIP_ControlBuf) consists of 9 contiguous words. You need to configure only some control words; other control words are read-only and are written to by the operation. In this example, the control array defines the operation as an unconnected explicit message, and identifies the target device:

CIP Request

The CIP request is located at the beginning of the databuffer and is followed by the CIP response. In this example, the CIP request calls for the return of a single attribute value (diagnostic data), and describes the request path through the target device’s object structure leading to the target attribute:

Combining the high and low bytes, above, the CIP request would look like this:

Viewing the Response

Use a Control Expert Animation table to display the EIP_DataBuf variable array. Note that the EIP_DataBuf variable array consists of the entire data buffer, which includes the:

• CIP request (4 words) located in EIP_DataBuf(1-4)

• CIP service type (1 word) located in EIP_DataBuf(5)

• CIP request status (1 word) located in EIP_DataBuf(6)

• CIP response (in this case, 10 words) located in EIP_DataBuf(7-16)

To display the CIP response, follow these steps:

Step	Action
1	In Control Expert, select Tools → Project Browser to open the Project Browser .
2	In the Project Browser, right-click Animation Tables > New Animation Table . Result: A new animation table opens.
3	In the New Animation Table dialog, edit the following values:
	Name	Type in a table name. For this example: EIP_DataBuf.
	Functional Mode	Accept the default <None>.
	Comment	Leave blank.
	Number of animated characters	Type 100, representing the size of the data buffer in words.
4	The completed dialog looks like this: Click OK to close the dialog.
5	In the animation table’s Name column, type in the name of the variable assigned to the databuffer: EIP_DataBuf and press Enter. The animation table displays the EIP_DataBuf variable.
6	Expand the EIP_DataBuf variable to display its word array, where you can view the CIP response at words EIP_DataBuf(7-16): Note: Each word presents 2 bytes of data in little endian format, where the least significant byte is stored in the smallest memory address. For example, ‘0E’ in EIP_DataBuf[0] is the low byte, and ‘03’ is the high byte.