Chapter 3: Installation and Initial Setup
Figure 3-24. Modbus Port screen.
c. “Attached”—This is selectable between Master and Slaves. If “Master” is selected, the Modbus Hardened Serial Server will run in TCP server mode, if “Slaves” is selected, it will run in TCP client mode.
d. “Modbus” indicates the protocol of the device connected to the port. It can be either RTU or ASCII.
e. ”Enable Modbus Broadcast”—Check this box to send Modbus broadcasts to a specific serial port. Modbus broadcast is Slave ID 0h. If selected, the Modbus Hardened Serial Server will send broadcast messages out the serial port and will not expect a response. If unselected, it will use slave ID 0h as a standard address.
f. “Enable 0Bh Exception”—Check this box to enable. When the Modbus slave device does not respond before the timeout has been reached or has a bad response (check sum does not match), the 0Bh exception code is transmitted to the Master that initiated the Modbus message.
g. “Enable Serial Message Buffering”—If this option is selected, the gateway will buffer up to 32 message requests per port. If this option is unselected, the Modbus Hardened Serial Server will respond with a 06h if it has a message out on the port with no response yet.
h. “Modbus Serial Retries”—Select 0 through 5. This sets the maximum number of times that the Modbus Hardened Serial Server will retry to send a Modbus message to a Modbus client, before reporting a 0Bh exception if it is selected. Number of retries is limited to 5.
i. “Milliseconds Modbus Message Timeout”—This is the maximum amount of time to wait for a response to the message. Valid value range is from 1 to 65535.
j. “Milliseconds TX Delay”—This is the minimum amount of time after receiving a response before the next message can be sent out. Valid value range is from 1 to 65535.
k. Save settings by clicking the “Save” button.
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