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Failure of RS485 communication between controller to xPortal Server
Author: Microengine Views: 13343 Created: 26-08-2015 11:19 AM 0 Rating/ Voters

This article contains the RS485 connection for controller XP-GT/ XP-GTR to xPortal Server PC.

Applies To:

  • XP-GT1200L, XP-GT3200L, XP-GT1200LABX, XP-GT3200LABX, XP-GT3200LE, XP-GT3200LCPX, XP-GT500LE, XP-GTR1200L, XP-GTR3200L  

Failure of RS485 communication between controller to xPortal Server.          


 Controller status shown "Down" in Device List.
 No transaction update in the software Latest Event List.
 Controller setting does not updated when download setting from the software.
 Software Delivery Report shows sent "Error" when download setting or update card user info to the controller.

 Cause (optional)
 MCI faulty.
 Comm Port faulty.
 Incorrect Comm Port No. selected.
 Incorrect controller Unit No./ System Addr No. set in the controller and software xPortal Server.
 Incorrect Baud Rate Setting in the controller, MCI and software xPortal Server.
 Loose connection between controller and MCI or USB to Serial Port converter.
 Incorrect wiring connection between controller to MCI or RS485 signal converter.

 Resolution Summary


  1. Connect the RS485 cable properly.
  2. Check the RS485 cable is working and in good condition.
  3. Power on the MCI and connect to the controller. Make sure the Comm Port is working.
  4. Check the Comm Port or USB to Serial converter is working.
  5. Make sure the driver of USB to serial converter has been installed correctly and detected by the Windows OS.

Server Software Setup:

  1. In Connection Setup,
    1. Set the Comm Port according to the Port No. connected to the machine.
    2. Set the Baud Rate/ Speed according to the MCI baud rate jumper settings.

  2. In Controller Setup, 
    1. Set the Controller's Unit No according to the System Addr. No in General Parameter of the controller.

  3. Configure to allow the software through Windows Firewall and antivirus.

Ensure the connection from controller to the PC is correct. Please refer to the connection guide below:

  1. Connect the controller to a RS485 cable as shown below.

  2. The controller connected to 1 unit of MCI must NOT more than 16 units.
  3. The distance from the MCI to this controller must NOT farther than 1km.
  4. Check the wiring connection from 1 MCI to each controller is connected to a single pair of RS485 (C+/ C-) cables or called Bus Network Topology.

  1. Set the correct System Address (ADDR) in the controller. 
    1. The address must be unique and does not same with other controllers' Address Unit No.
    2. To enter the XP-GT/ XP-GTR Programming Mode, see article small How to enter to XP-GT/ XP-GTR Programming Menu?

  2. Configure the controller from the Server software.
    1. To configure server setup using RS485, see small How to configure the XP-GT/ XP-GTR controller using RS485/ RS232 connection?
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