Comtrol Modbus TCP Quick Start User Manual
Page 50
50 - Configuring Read/Write Raw/ASCII Devices
DeviceMaster UP Modbus/TCP Quick Start: 2000477 Rev. G
Configuring Read/Write Raw/ASCII Devices
6.
Set the Message Transfer mode:
•
Selecting Data-Stream will enable asynchronous communication to the device.
-
Transmit data will be 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 N/A (not applicable).
•
Selecting Command/Response will enable 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 Cmd/Resp 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.
7.
Set up the Socket Packet Identification.
a.
Set the Rx Timeout Between Packets. Set to zero to stream data with the Rx STX/ETX Detect settings set
to none. For normal settings, typical values are 10 to 50 ms.
b.
Set the STX (Start of transmission) Rx Detect in decimal format.
c.
Set the ETX (End of transmission) Rx Detect in decimal format.
d.
Enable the Strip Rx STX/ETX option if you do not want the STX and ETX bytes returned to the PLC or
application.
Note: Refer to your device's User Manual for the Start and End of Transmission byte(s) settings.