Comtrol Modbus TCP Quick Start User Manual

Page 38

38 - Configuring Read/Write Raw/ASCII Devices

DeviceMaster UP Modbus/TCP Quick Start: 2000477 Rev. G

Configuring Read/Write Raw/ASCII Devices

Set up the Serial Configuration for your device.

Select the Modbus/TCP communication method and set up the Modbus/TCP Interface settings under
General Protocol Settings:

Set Serial Port Protocol to Raw-Data.

Enable Discard Rx Packets With Errors.

Set the Raw-Data Message Transfer mode:

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Selecting Data-Stream enables asynchronous communication to the device.

Transmit data is sent immediately from all Modbus and active Application interfaces.

Received data will be returned to the Modbus interface and all active Application interfaces.

If Data-Stream is selected, the rest of the options in this section are not applicable.

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Selecting Command/Response enables synchronous communications with the device.

Transmit data will expect one or more responses.

Responses will only be returned to the transmit message originator.

If Command/Response is selected:

Set the Response Timeout to a valid timeout period for your device.

The Cmd/Resp Age Time will set the time at which old responses to the Modbus interface are
discarded.

The Cmd/Resp Expected Responses Per Command indicates the number of responses expected per
transmitted message. This is typically 1.

Set the Cmd/Resp Mode Response To Modbus/TCP Based On option to:

IP-Address if there is only one Modbus/TCP interface per IP-Address communicating to this
port. This is typically used for PLC or single OPC Server/SCADA systems.

TCP-Connection if there is more than one Modbus/TCP interface per IP-Address
communicating to this port. This typically is required for multiple OPC Server/ SCADA
systems running on the same computer.