ITW EAE Support Center

Protocol 3 RS-485 Setup

1.  If using a USB-to-serial adapter, install the necessary drivers for the adapter.   If the adapter supports multiple serial protocols (RS-232, RS-485, RS-422), refer to the adapter documentation to properly configure for two-wire, half-duplex RS-485.  If using other passive adapters to convert RS-232 to RS-485, verify the pin-out and proper connections are used for RS-485.

2.  Open Windows Device Manager and identify the COMx addresses available to Windows.  When USB-to-Serial adapters are installed they are easily identified.

 3.  Connect the proper cabling and setup any serial adapters for RS-485 (two-wire, half-duplex).  Refer to vendor documentation for any serial adapters.

4.  Connect the two wires from the RS-485 serial port to the Protocol 3™, terminals 19 and 20.  Follow proper RS-485 wiring polarity between serial port and Protocol 3™.  If the wire polarity is incorrect communication will not work. For details on Protocol 3™ wiring refer to the Protocol 3™ documentation.

5.  Open Despatch Protocol Manager software and log in with Level 4 (highest) password.

6.  From the top Window menu select Setup.

  7.  Select the Comm Setup tab.  Set the Port Selection value to the serial port of the PC connected to the Protocol 3™.


If there are multiple Communications Port (COMx) entries in Windows Device Manager, and no identification on the case of the PC for each port, each COMx address will have to be tried until successful communication.  If using a USB-to-serial adapter, select the USB Serial Port (COMx) address matching that of the adapter.  If there are multiple USB Serial Ports listed in Windows Device Manger it is easier to identify a USB serial port by unplugging the USB cable and seeing what disappears or remains in the Device Manager list.


 8.  Press the Accept button after setting the Port Selection.

9.  Select the proper Baud Rate and Parity settings matching the settings configured in the Protocol 3™.  For details setting up Protocol 3™ communication settings, refer to the Protocol 3™ documentation.

10.  Select Accept after changing settings.

11.  Open the Network tab.

12.  There needs to be at least one controller setup.  Either Insert a new controller or Edit an existing controller listed.

 13.  Set a name for the controller.

14.  Set the Address number, matching the address configured in the Protocol 3™.

15.  Set the Controller Type to Protocol 3™.

16.  Set the check box to Enable Communication.

17.  Press the Set button.

18.  Press the Accept button of the Setup window if not grayed out to accept any other pending settings.

19.  If wiring, serial port, and Protocol 3™ are properly setup, communication will begin immediately.


  • If not communicating, double check the communication settings, described above, match those set in the Protocol 3™.
  • If communication settings in both Protocol Manager and Protocol 3™ match, then it is most likely a serial port setting or wiring issue.
  • If using a USB-to-serial adapter such as a USB-COMi-M device (Despatch PN 9-305401) the adapter has LEDs to assist communication debug.
    1. If the TX LED is blinking, then Protocol Manager is talking to that serial port.
    2. If the TX LED is not blinking, then the incorrect port is specified in Protocol Manager, or the serial port is not properly setup in Windows.
    3. If the TX LED is blinking, but the RX LED is not, this usually means the two RS-485 wires are connected backwards.   Swap the polarity on one end of the link to see if communication is established.
  • If using a serial adapter or PC serial port that does not provide TX/RX diagnostics, then you can only try each COMx address listed in Windows Device Manager to find the one that works.  However, if the wiring is incorrect this will still not result in a successful link.
MyLinda is the author of this solution article.

Did you find it helpful? Yes No

Send feedback
Sorry we couldn't be helpful. Help us improve this article with your feedback.