Using Panel Software
4.1Using Concept or Modsoft
4.1.1Software Versions
To support Modbus/TCP to the Bridge, you need Concept version 2.1 or later, or Modsoft version 2.6 or later. Set the communications parameters as follows:
HProtocol: TCP/IP
HDest_Port: 502
HDest_Index: Modbus Slave address
Note that the Bridge contains an internal Slave Address configuration option which might affect the delivery of messages to a Slave device at its serial port.
With this option, the Bridge may be configured internally to use the Dest_Index address exactly as received in the message, or it may be configured to steer all messages to a fixed Slave address, ignoring the Dest_Index address.
HTCP/IP Address: as required.
4.1.2Modbus Slave Address
This is an additional explanation of how the Bridge uses the Modbus Slave address.
In a Modbus TCP message sent to the Bridge, the Slave address (defined in panel software as the Dest_Index address) is stored in the Unit_ID field of the message. This field is used to address a unique Slave device on a Modbus network which may contain multiple Slave devices.
The Bridge's internal configuration contains a Slave Address parameter which can be set to override the Unit_ID address received in the message. Section 3.9 of this book describes how to set up the Slave Address parameter.
If the parameter is set to 0 (zero), the message will be delivered to the Slave device whose address is defined in the Unit_ID field. If the parameter is set to a non±zero value (range 1 ... 255), the message will be delivered to the Slave device at that numerical address, regardless of the contents of the Unit_ID field.
For example: If you are accessing the device at Modbus Slave address 34, you must:
HSet the Dest_Index field to 34, and
HEnsure the Bridge's internal Slave Address parameter is configured to 0 (zero).
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