Sending Explicit Messages to Modbus TCP Devices
Original instructions
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Overview
Use the Modbus Explicit Message window in the Control Expert DTM to send an explicit message from an EtherNet/IP module or distributed device on the network.
You can use explicit messaging to perform many different services. Not every Modbus TCP device supports every service.
The Modbus TCP explicit message configuration window shows both the configuration of a Modbus TCP explicit message and the response.
Sending Explicit Messages
Execute a Modbus TCP explicit message:
Step
Action
1
In the DTM Browser, select the communication module that is upstream of the target device.
2
Right-click the module and select Device menu → Additional functions → Modbus TCP Explicit Message.
3
Configure explicit messages in these fields:
IP Address
The IP address of the target device, used to identify the target of the explicit message.
Start Address
A component of the addressing path.
Quantity
A component of the addressing path.
Read Device Id Code
Read-only identification of the service that the explicit message is intended to perform.
Object Id
(read-only) Specify the object the explicit message is intended to access.
Refer to your Modbus TCP device user manual for Start Address, Quantity, Read Device Id Code, and Object Id values.
Unit Id
The Unit ID is the number used to identify the target of the connection.
NOTE: Consult the manufacturer’s user manual for the specific target device to find its Unit ID.
Number
The read-only integer (0 ... 255) associated with the service to be performed by the explicit message.
Name
Select the service the explicit message is intended to perform.
Repeat 500ms
Select this check box to re-send the explicit message every 500 ms. Leave this check box de-selected.
4
After your explicit message is configured, click Send to Device.
Data in the Response area was sent to the configuration tool by the target device in hexadecimal format.
Messages in the Status area indicate whether or not the explicit message has succeeded.
5
Click Close to close the window.