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Reset a BACnet B4920 back to the factory default IP address


How do I reset my BACnet B4920 back to the factory default IP address?




There is no Reset IP switch on the B4920


There are 2 ways of accomplishing this.

Method One - The first method resets controller to factory default address settings:

IP Address:
Subnet Mask:
Webserver Port: 80
Web User Name: acc
Web User pwd: acc
EnergyNet ID: 1
BacNetMstpNetId: 2764
BacNetUDPNetId: 2765

During controller startup, there is a 2 minute window in which the controller will be restored to factory defaults based on the following:

  1. Seconds since startup is < 120
  2. A Ping packet is received by the controller with a matching Ethernet address but unmatched IP address.
  3. Ping payload size of 255 bytes.

Prior to running the procedure, the controller must be on the same network as the PC that that is used to issue commands.

Prior to running the procedure, you will need to have on hand (1) IP address that is both valid and NOT in use on the network that the PC and Controller are connected to.

  1. Get the Controller's MAC Address

    Each controller has a 6 byte hardware address, also known as the MAC address or Ethernet address. The address is represented in HEX. The first three bytes of the MAC address are constant and represent Andover Controls vendor ID : 00-40-11
    The last 3 bytes of the MAC address are derived from your controller’s serial number. The controller’s serial number is printed on the board and is represented as an Integer value. You must convert this value to HEX in order to obtain the last 3 bytes of your controllers MAC address.
    Ex. Integer Serial Number: 1033394
    Converted to Hex: FC4B2

    Controller’s MAC: 00-40-11-0F-C4-B2
  2. Create a batch file
    Create a batch file named Acc.bat with the following content:

    arp -s %1 %2
    ping -l %3 %1
    arp -d %1
  3. Restart the B4xxx Controller

    Within 2 Minutes of restarting, run the batch file with the 3 arguments:

    Acc.bat IP_Address 00-40-11-XX-XX-XX 255

    Where IP_Address = valid IP on the network
    Where XX-XX-XX = last 3 bytes of controller’s MAC
    Where 255 = Ping Payload size

  4. After Issuing the command, the controller should restart, and the factory default address settings are restored. 


Method Two - Capture the Controllers Currently Configured IP Address

This second method is easier to do and is what is recommended because of its ease.

  1. Download and install a network sniffing application. We most commonly use Wireshark which can be downloaded from their website here.
  2. Connect a Cross over Ethernet cable between the B4920 and the PC running the network sniffing application.
  3. Start up the network sniffing application and then reset the B4920 by hitting the reset button on the controller.

What will happen is that on the start up of the controller the controller will send out the IP address (Gratuitous ARP Packet) it currently has assigned to it. Once you capture this IP address with the network sniffing application you can change the IP of your workstation and get to the controller's web configuration page to change the IP address.

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Last update:
‎2018-09-07 12:39 AM
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