Overview

The following unconnected explicit messaging example shows you how to use the DATA_EXCH function block to retrieve diagnostic data from a remote device (at IP address 192.168.1.6). This example is executing a Get_Attribute_Single of assembly instance 100, attribute 3.

You can perform the same explicit messaging service using the EtherNet/IP Explicit Message window.

Implementing the DATA_EXCH Function Block

To implement the DATA_EXCH function block, create and assign variables for the following blocks:

Configuring the Address Variable

The Address variable identifies the explicit message originating device (in this example, the communication module) and the target device. Note that the Address variable does not include the Xway address elements {Network.Station} because we are not bridging through another PLC station. As an example, use the ADDM function to convert the following character string to an address:

ADDM(‘0.1.0{192.168.1.6}UNC.CIP’), where:

  • rack = 0

  • module (slot number) = 1

  • channel = 0

  • remote device IP address = 192.168.1.6

  • message type = unconnected

  • protocol = CIP

Configuring the ActionType Variable

The ActionType variable identifies the function type for the DATA_EXCH function block:

Variable

Description

Value (hex)

ActionType

Transmission followed by wait for response

16#01

Configuring the DataToSend Variable

The DataToSend variable identifies the details of the CIP explicit message request:

Variable

Description

Value (hex)

DataToSend[0]

CIP request service information:

  • High byte = request size in words: 16#03 (3 decimal)

  • Low byte = service code: 16#0E (14 decimal)

16#030E

DataToSend[1]

CIP request class information:

  • High byte = class: 16#04 (4 decimal)

  • Low byte = class segment: 16#20 (32 decimal)

16#0420

DataToSend[2]

CIP request instance information:

  • High byte = instance: 16#64 (100 decimal)

  • Low byte = instance segment: 16#24 (36 decimal)

16#6424

DataToSend[3]

CIP request attribute information:

  • High byte = attribute: 16#03 (3 decimal)

  • Low byte = attribute segment: 16#30 (48 decimal)

16#0330

Viewing the Response

Use a Control Expert Animation table to display the ReceivedData variable array. Note that the ReceivedData variable array consists of the entire data buffer.

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, select the Animation Tables folder, then click the right mouse button. A pop-up menu appears.

3

Select New Animation Table in the pop-up menu. A new animation table and its properties dialog both open.

4

In the Properties dialog, edit the following values:

Name

Type in a table name. For this example: ReceivedData.

Functional module

Accept the default <None>.

Comment

(Optional) Type your comment here.

Number of animated characters

Type in 100, representing the size of the data buffer in words.

5

Click OK to close the dialog.

6

In the animation table’s Name column, type the name of the variable assigned to the RECP pin: ReceivedData and press Enter. The animation table displays the ReceivedData variable.

7

Expand the ReceivedData variable to display its word array, where you can view the CIP response contained in the ReceivedData variable.

NOTE: Each array entry presents 2 bytes of data in little endian format, where the least significant byte is stored in the smallest memory address. For example, ‘8E’ in word[0] is the lower byte, and ‘00’ is the upper byte.