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Configuring Serial Communications Setup

A WebPort provides RS-232/RS-485 serial communications via two ports, Port 1 and Port 2. You may connect the WebPort via these ports to external programmable logic controllers (PLCs) or other devices.

The WebPort has two serial ports, Serial 1 and Serial 2. You use these to provide serial communications between a WebPort and PLCs or other control devices. WebPorts supports multiple serial protocols, including DF1-CIP, DF1-PCCC, Modbus RTU, Modbus ASCII, and PPI.

WebPort also provides a pass-through protocol conversion capability that converts the PCCC or EtherNet/IP protocol to the DF1 serial protocol. This capability is also provided for the supported Modbus protocols. In this instance, the pass-through capability converts the Modbus TCP protocol to the Modbus RTU serial protocol.

When the Passthrough capability is enabled, WebPort takes incoming Ethernet packets from the WebPort's WAN port and converts them to serial packets. The WebPort then sends the packets out via the associated WebPort serial port. The WebPort also converts packets received from a serial port to Ethernet packets that are then transmitted via the WAN port. You can use RSLogix software to access the PLC using one of the WebPort's serial ports remotely via the WAN. The same applies to a PLC using a Modbus protocol. The WebPort is able to access Modbus serial devices that use the Modbus TCP protocol remotely via the WAN.

From V1.1, WebPort supports 5- and 6-digit Modbus addressing. The 5- and 6-digit addressing refers to the range of references in the device. The leading digit "0" for an internal coil or discrete output, "1" for a discrete input, 3" for an analog input, and "4" for a holding register or analog output, is not part of the address. It is a data type, not a number. For 5-digit addressing, 40000 to 49999, the actual range is 10,000, 0 to 9999. For 6-digit addressing, 400000 to 499999, the actual range is 100,000, 0 to 99999 . If you want to read holding register 2345, you can either use address 42345 in 5-digit mode or use address 402345 in 6-digit mode as they are the same. If you want to read holding register 12345, you have to use 6-digit mode address 412345.

To configure serial ports for the WebPort:

  1. From the Configuration Work Area, select the following icon: This is a picture of the dialog. The Serial Communications Setup dialog appears: This is a picture of the dialog.
  2. View or specify the following Communications Settings options for each serial port Serial Port 1 or Serial Port 2:
    • Baud Rate. Specifies the speed at which the serial port sends data. Rates are 1200 through 115200. Select the desired rate from the dropdown menu.
    • Data Bits. Specifies word length. Lengths are 7 or 8 bits. Select the desired length from the dropdown menu.
    • Stop Bits. Specifies number of stop bits to use. Numbers are 1 or 2. Select the desired number from the dropdown menu.
    • Parity. Specifies parity to use. Options are none, odd, or even. Select the desired option from the dropdown menu.
    • Handshake. Defines whether or not to use handshaking, and the handshaking type. Options are none, RTS/CTS, X-ON/X-OFF. Select the desired option from the dropdown menu.
    • Connection Type. Defines whether to use the WebPort's RS-232 or RS-485 serial communication. RS-232 is a point-to-point protocol (can only connect one device per port) that usually runs on cables shorter than fifty feet, and may be susceptible to noise. Select this option for point-to-point communication on the serial port. The WebPort Device ID is always zero (0) and the external PLC device is usually 1. RS-485 is a multi-drop protocol (up to thirty-two devices per port), that runs up to five hundred feet (or more with repeaters), and is noise resistant. Select this option for multi-point network communication or for S7-200 PPI communications. With RS-485, the external PLC devices can have different device IDs.
    • Pass-thru Enabled. Specifies whether or not to allow pass through. When Passthrough is enabled, the WebPort converts the packets received from the WAN to packets that can be sent out via serial ports. Depending on the selection, the WebPort converts the DF1 Ethernet packets to DF1 serial, or Modbus TCP packets to Modbus RTU.

      When selected, the following options are enabled:

      • Protocol. Defines protocol to use:
        • DF1-CIP. DF1-CIP is an asynchronous RS-232 serial protocol used to communicate with ControlLogix and CompactLogix Allen Bradley RS-232 interface modules. (You normally use RSLogix 5000 to work with these types of PLC.)
          • Slave ID. Station number of your PLC on the network. It is usually 1 if you are not connecting the WebPort serial port to an RS-485 network.
          • Checksum. Rockwell PLC DF1 protocol supports CRC and BCC checksum methods. Please check your PLC setting to find out the checksum method PLC uses. By default, the protocol setting is CRC.
        • DF1-PCCC. DF1-PCCC is an asynchronous RS-232 serial protocol used to communicate with non-Logix Allen Bradley RS-232 interface modules such as PLC5 or MicroLogix. (You normally use RSLogix 500 to work with these types of PLC.)
          • Slave ID. Station number of your PLC on the network. It is usually 1 if you are not connecting the WebPort serial port to an RS-485 network.
          • Checksum. Rockwell PLC DF1 protocol supports CRC and BCC checksum methods. Please check your PLC setting to find out the checksum method PLC uses.
        • ModbusRTU. Modbus is a serial communications protocol that allows a personal computer or other device to communicate with up to two-hundred and forty programmable logic controllers that measure conditions such as temperature and humidity.
          • Slave ID. Station number of your PLC on the network. It is usually 1 if you are not connecting the WebPort serial port to an RS-485 network.
        • ModbusASCII. Modbus serial communications protocol as above, but uses ASCII characters instead of binary.
          • Slave ID. Station number of your PLC on the network. It is usually 1 if you are not connecting the WebPort serial port to an RS-485 network.
        • PPI. PPI protocol. Use for Siemens S7-200 PLC. Only accessible when RS-485 is selected. If you choose this option when adding devices, the software informs you that you must first select RS-232 for the serial port.
        View only option:
        • Slave ID. Station number of your PLC on the network. Because the PPI protocol uses RS-485 to communicate, Slave ID for the protocol is automatically set to 2.
  3. Submit. Saves the entered connection data on WebPort. The software informs you that the data settings were successfully modified. Click OK.
  4. Cancel. Exits without saving data from WebPort.

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