Configure the Modbus gateway

Required configuration items

Additional configuration items


  1. Log into Digi Remote Manager, or log into the local Web UI as a user with full Admin access rights.
  2. Access the device configuration:

    1. Locate your device as described in Use Digi Remote Manager to view and manage your device.
    2. Click the Device ID.
    3. Click Settings.
    4. Click to expand Config.

    1. On the menu, click System. Under Configuration, click Device Configuration.

      The Configuration window is displayed.

  3. Click Services > Modbus Gateway.

  4. Click Enable to enable the gateway.
  5. Click Debug to allow verbose logging in the system log.

Configure gateway servers

  1. Click to expand Gateway Servers.
  2. For Add Modbus server, type a name for the server and click .

    The new Modbus gateway server configuration is displayed.

  3. The new Modbus gateway server is enabled by default. Toggle off Enable the server to disable.
  4. For Connection type, select Socket or Serial. Available options in the gateway server configuration vary depending on this setting.
    • If Socket is selected for Connection type:
      1. For IP Protocol, select TCP or UDP. The default is TCP.
      2. For Port, enter or select an appropriate port. The default is port 502.
    • If Serial is selected for Connection type:
      1. For Serial port, select the appropriate serial port on the EX15 device.
  5. For Packet mode, select RTU or RAW (if Connection type is set to Socket) or ASCII (if Connection typeis set to Serial) for the type of packet that will be used by this connection. The default is RTU.
  6. For Packet idle gap, type the maximum allowable time between bytes in a packet.

    Allowed values are between 10 milliseconds and one second, and take the format number{ms|s}.

    For example, to set Packet idle gap to 20 milliseconds, enter 20ms.

  7. If Connection type is set to Socket, for Inactivity timeout, type the amount of time to wait before disconnecting the socket when it has become inactive.

    Allowed values are any number of minutes or seconds up to a maximum of 15 minutes, and take the format number{m|s}.

    For example, to set Inactivity timeout to ten minutes, enter 10m or 600s.

  8. (Optional) If Connection type is set to Serial, click Half duplex to enable half duplex (two wire) mode.
    • To limit access to specified IPv4 addresses and networks:
      1. Click IPv4 Addresses.
      2. For Add Address, click .
      3. For Address, enter the IPv4 address or network that can access the device's web administration service. Allowed values are:
        • A single IP address or host name.
        • A network designation in CIDR notation, for example, 192.168.1.0/24.
        • any: No limit to IPv4 addresses that can access the web administration service.
      4. Click again to list additional IP addresses or networks.
    • To limit access to specified IPv6 addresses and networks:
      1. Click IPv6 Addresses.
      2. For Add Address, click .
      3. For Address, enter the IPv6 address or network that can access the device's web administration service. Allowed values are:
        • A single IP address or host name.
        • A network designation in CIDR notation, for example, 2001:db8::/48.
        • any: No limit to IPv6 addresses that can access the web administration service.
      4. Click again to list additional IP addresses or networks.
    • To limit access to hosts connected through a specified interface on the device:
      1. Click Interfaces.
      2. For Add Interface, click .
      3. For Interface, select the appropriate interface from the dropdown.
      4. Click again to allow access through additional interfaces.
    • To limit access based on firewall zones:
      1. Click Zones. By default, there are three firewall zones already configured: Internal, Edge, and IPsec.
      2. For Add Zone, click .
      3. For Zone, select the appropriate firewall zone from the dropdown.

        See Firewall configuration for information about firewall zones.

      4. Click again to allow access through additional firewall zones.
  10. Repeat these steps to configure additional servers.

Configure clients

  1. Click to expand Clients.
  2. For Add Modbus client, type a name for the client and click .

    The new Modbus gateway client configuration is displayed.

  3. The new Modbus gateway client is enabled by default. Toggle off Enable the client to disable.
  4. For Connection type, select Socket or Serial. Available options in the gateway server configuration vary depending on this setting.
    • If Socket is selected for Connection type:
      1. For IP Protocol, select TCP or UDP. The default is TCP.
      2. For Port, enter or select an appropriate port. The default is port 502.
      3. For Remote host, type the hostname or IP address of the remote host on which the Modbus server is running.
    • If Serial is selected for Connection type:
      1. For Serial port, select the appropriate serial port on the EX15 device.
  5. For Packet mode, select RTU or RAW (if Connection type is set to Socket) or ASCII (if Connection typeis set to Serial) for the type of packet that will be used by this connection. The default is RTU.
  6. For Packet idle gap, type the maximum allowable time between bytes in a packet.

    Allowed values are between 10 milliseconds and one second, and take the format number{ms|s}.

    For example, to set Packet idle gap to 20 milliseconds, enter 20ms.

  7. If Connection type is set to Socket, for Inactivity timeout, type the amount of time to wait before disconnecting the socket when it has become inactive.

    Allowed values are any number of minutes or seconds up to a maximum of 15 minutes, and take the format number{m|s}.

    For example, to set Inactivity timeout to ten minutes, enter 10m or 600s.

  8. (Optional) If Connection type is set to Serial, click Half duplex to enable half duplex (two wire) mode.
    • To limit access to specified IPv4 addresses and networks:
      1. Click IPv4 Addresses.
      2. For Add Address, click .
      3. For Address, enter the IPv4 address or network that can access the device's web administration service. Allowed values are:
        • A single IP address or host name.
        • A network designation in CIDR notation, for example, 192.168.1.0/24.
        • any: No limit to IPv4 addresses that can access the web administration service.
      4. Click again to list additional IP addresses or networks.
    • To limit access to specified IPv6 addresses and networks:
      1. Click IPv6 Addresses.
      2. For Add Address, click .
      3. For Address, enter the IPv6 address or network that can access the device's web administration service. Allowed values are:
        • A single IP address or host name.
        • A network designation in CIDR notation, for example, 2001:db8::/48.
        • any: No limit to IPv6 addresses that can access the web administration service.
      4. Click again to list additional IP addresses or networks.
    • To limit access to hosts connected through a specified interface on the device:
      1. Click Interfaces.
      2. For Add Interface, click .
      3. For Interface, select the appropriate interface from the dropdown.
      4. Click again to allow access through additional interfaces.
    • To limit access based on firewall zones:
      1. Click Zones. By default, there are three firewall zones already configured: Internal, Edge, and IPsec.
      2. For Add Zone, click .
      3. For Zone, select the appropriate firewall zone from the dropdown.

        See Firewall configuration for information about firewall zones.

      4. Click again to allow access through additional firewall zones.
  10. (Optional) Enable Send broadcast messages to configure the gateway to send broadcast messages to this client.
  11. For Response timeout, type the maximum time to wait for a response to a message.

    Allowed values are between 1 millisecond and 700 milliseconds, and take the format numberms.

    For example, to set Response timeout to 100 milliseconds, enter 100ms. The default is 700ms.

  12. Click to expand Modbus address filter.

    This filter is used by the gateway to determine if a message should be forwarded to a destination device. If the Modbus address in the message matches one or more of the filters, the message is forwarded. If it does not match the filters, the message is not forwarded.

  13. For Address or address range, type a Modbus address or range of addresses. Allowed values are 1 through 255 or a hyphen-separated range.

    For example, to have this client filter for incoming messages that contain the Modbus address of 10, type 10. To filter for all messages with addresses in the range of 20 to 30, type 20-30.

    To add additional address filters for this client, click .

  14. For Fixed Modbus server address, if request messages handled by this client should always be forwarded to a specific device, type the device's Modbus address. Leave at the default setting of 0 to allow messages that match the Modbus address filter to be forwarded to devices based on the Modbuss address in the message.
  15. For Adjust Modbus server address, type a value to adjust the Modbus server address downward by the specified value prior to delivering the message. Allowed values are 0 through 255. Leave at the default setting of 0 to not adjust the server address.

    If a packet contains a Modbus server address above the amount entered here, the address will be adjusted downward by this amount before the packet is delivered. This allows you to configure clients on the gateway that will forward messages to remote devices with the same Modbus address on different buses. For example, if there are two devices on two different buses that have the same Modbus address of 10, you can create two clients on the gateway:

    • Client one:
      • Modbus address filter set to 10.

      This will configure the gateway to deliver all messages that have the Modbus server address of 10 to this device.

    • Client two:
      • Modbus address filter set to 20.
      • Adjust Modbus server address set to 10.

      This will configure the gateway to deliver all messages that have the Modbus server address address of 20 to the device with address 10.

  16. Repeat these steps to configure additional clients.

  17. Click Apply to save the configuration and apply the change.
  1. Select the device in Remote Manager and click Actions > Open Console, or log into the EX15 local command line as a user with full Admin access rights.

    Depending on your device configuration, you may be presented with an Access selection menu. Type admin to access the Admin CLI.

  2. At the command line, type config to enter configuration mode:

    > config
(config)>

  3. Enable the Modbus gateway:
    (config)> service modbus_gateway enable true
(config)>
  4. Configure servers:
    1. Add a server:
      (config)> add service modbus_gateway server name
(config service modbus_gateway  server name)>

      where name is a name for the server, for example:

      (config)> add service modbus_gateway server test_modbus_server
(config service modbus_gateway server test_modbus_server)>

      The Modbus server is enabled by default. To disable:

      (config service modbus_gateway server test_modbus_server)> enable false
(config service modbus_gateway server test_modbus_server)>

    2. Set the connection type:
      (config service modbus_gateway server test_modbus_server)> connection_type type
(config service modbus_gateway server test_modbus_server)>

      where type is either socket or serial. The default is socket.

      • If connection_type is set to socket:
        1. Set the IP protocol:
          (config service modbus_gateway server test_modbus_server)> socket protocol value
(config service modbus_gateway server test_modbus_server)>

          where value is either tcp or udp.

        2. Set the port:
          (config service modbus_gateway server test_modbus_server)> socket port
(config service modbus_gateway server test_modbus_server)>

          where port is an integer between 1 and 65535. The default is 502.

        3. Set the packet mode:
          (config service modbus_gateway server test_modbus_server)> socket packet_mode value
(config service modbus_gateway server test_modbus_server)>

          where value is either rtu or raw. The default is rtu.

        4. Set the maximum allowable time between bytes in a packet:
          (config service modbus_gateway server test_modbus_server)> socket idle_gap value
(config service modbus_gateway server test_modbus_server)>

          where value is any number between 10 milliseconds and one second, and take the format number{ms|s}.

          For example, to set idle_gap to 20 milliseconds, enter 20ms.

        5. Set the amount of time to wait before disconnecting the socket when it has become inactive:
          (config service modbus_gateway server test_modbus_server)> inactivity_timeout value
(config service modbus_gateway server test_modbus_server)>

          where value is any number of minutes or seconds up to a maximum of 15 minutes, and takes the format number{m|s}.

          For example, to set inactivity_timeout to ten minutes, enter either 10m or 600s:

          (config service modbus_gateway server test_modbus_server)> inactivity_timeout 600s
(config service modbus_gateway server test_modbus_server)>
      • If connection_type is set to serial:
        1. Set the serial port:
          1. (config service modbus_gateway server test_modbus_server)> ... serial port ?

Serial

  Additional Configuration
  -------------------------------------------------------------------------------
  port1                     Port 1

(config service modbus_gateway server test_modbus_server)>
          2. Set the port:
            (config service modbus_gateway server test_modbus_server)> serial port
(config service modbus_gateway server test_modbus_server)>
        2. Set the packet mode:
          (config service modbus_gateway server test_modbus_server)> serial packet_mode value
(config service modbus_gateway server test_modbus_server)>

          where value is either rtu or ascii. The default is rtu.

        3. Set the maximum allowable time between bytes in a packet:
          (config service modbus_gateway server test_modbus_server)> serial idle_gap value
(config service modbus_gateway server test_modbus_server)>

          where value is any number between 10 milliseconds and one second, and take the format number{ms|s}.

          For example, to set idle_gap to one second, enter 1000ms or 1s.

        4. (Optional) Enable half-duplex (two wire) mode: 
          (config service modbus_gateway server test_modbus_server)> serial half_duplex true
(config service modbus_gateway server test_modbus_server)>
    3. Repeat the above instructions for additional servers.
  5. Configure clients:
    1. Type ... to return to the root of the configuration:
      (config)> add service modbus_gateway server test_modbus_server)> ...
(config)>
    2. Add a client:
      (config)> add service modbus_gateway client name
(config service modbus_gateway  client name)>

      where name is a name for the client, for example:

      (config)> add service modbus_gateway client test_modbus_client
(config service modbus_gateway client test_modbus_client)>

      The Modbus client is enabled by default. To disable:

      (config service modbus_gateway client test_modbus_client)> enable false
(config service modbus_gateway client test_modbus_client)>

    3. Set the connection type:
      (config service modbus_gateway client test_modbus_client)> connection_type type
(config service modbus_gateway client test_modbus_client)>

      where type is either socket or serial. The default is socket.

      • If connection_type is set to socket:
        1. Set the IP protocol:
          (config service modbus_gateway client test_modbus_client)> socket protocol value
(config service modbus_gateway client test_modbus_client)>

          where value is either tcp or udp.

        2. Set the port:
          (config service modbus_gateway client test_modbus_client)> socket port
(config service modbus_gateway client test_modbus_client)>

          where port is an integer between 1 and 65535. The default is 502.

        3. Set the packet mode:
          (config service modbus_gateway client test_modbus_client)> socket packet_mode value
(config service modbus_gateway client test_modbus_client)>

          where value is either rtu or ascii. The default is rtu.

        4. Set the maximum allowable time between bytes in a packet:
          (config service modbus_gateway client test_modbus_client)> socket idle_gap value
(config service modbus_gateway client test_modbus_client)>

          where value is any number between 10 milliseconds and one second, and take the format number{ms|s}.

          For example, to set idle_gap to 20 milliseconds, enter 20ms.

        5. Set the amount of time to wait before disconnecting the socket when it has become inactive:
          (config service modbus_gateway client test_modbus_client)> inactivity_timeout value
(config service modbus_gateway client test_modbus_client)>

          where value is any number of minutes or seconds up to a maximum of 15 minutes, and takes the format number{m|s}.

          For example, to set inactivity_timeout to ten minutes, enter either 10m or 600s:

          (config service modbus_gateway client test_modbus_client)> inactivity_timeout 600s
(config service modbus_gateway client test_modbus_client)>
        6. Set the hostname or IP address of the remote host on which the Modbus server is running:
          (config service modbus_gateway client test_modbus_client)> remote_host ip_address|hostname
(config service modbus_gateway client test_modbus_client)>
      • If connection_type is set to serial:
        1. Set the serial port:
          1. (config service modbus_gateway client test_modbus_client)> ... serial port ?

Serial

  Additional Configuration
  -------------------------------------------------------------------------------
  port1                     Port 1

(config service modbus_gateway client test_modbus_client)>
          2. Set the port:
            (config service modbus_gateway client test_modbus_client)> serial port
(config service modbus_gateway client test_modbus_client)>
        2. Set the packet mode:
          (config service modbus_gateway client test_modbus_client)> serial packet_mode value
(config service modbus_gateway client test_modbus_client)>

          where value is either rtu or ascii. The default is rtu.

        3. Set the maximum allowable time between bytes in a packet:
          (config service modbus_gateway client test_modbus_client)> serial idle_gap value
(config service modbus_gateway client test_modbus_client)>

          where value is any number between 10 milliseconds and one second, and take the format number{ms|s}.

          For example, to set idle_gap to one second, enter 1000ms or 1s.

        4. (Optional) Enable half-duplex (two wire) mode: 
          (config service modbus_gateway client test_modbus_client)> serial half_duplex true
(config service modbus_gateway client test_modbus_client)>
    4. (Optional) Enable the gateway to send broadcast messages to this client:
      (config service modbus_gateway client test_modbus_client)> broadcast true
(config service modbus_gateway client test_modbus_client)>
    5. Set the maximum time to wait for a response to a message:
      (config service modbus_gateway client test_modbus_client)> response_timeout value
(config service modbus_gateway client test_modbus_client)>

      Allowed values are between 1 millisecond and 700 milliseconds, and take the format numberms.

      For example, to set response_timeout to 100 milliseconds:

      (config service modbus_gateway client test_modbus_client)> response_timeout 100ms
(config service modbus_gateway client test_modbus_client)>

      The default is 700ms.

    6. Configure the address filter:

      This filter is used by the gateway to determine if a message should be forwarded to a destination device. If the Modbus address in the message matches one or more of the filters, the message is forwarded. If it does not match the filters, the message is not forwarded. Allowed values are 1 through 255 or a hyphen-separated range.

      For example:

      • To have this client filter for incoming messages that contain the Modbus address of 10, set the index 0 entry to 10:
        (config service modbus_gateway client test_modbus_client)> filter 0 10
(config service modbus_gateway client test_modbus_client)>

      • To filter for all messages with addresses in the range of 20 to 30, set the index 0 entry to 20-30:
        (config service modbus_gateway client test_modbus_client)> filter 0 20-30
(config service modbus_gateway client test_modbus_client)>

      To add additional filters, increment the index number. For example, to add an additional filter for addresses in the range of 50-100:

      (config service modbus_gateway client test_modbus_client)> filter 1 50-100
(config service modbus_gateway client test_modbus_client)>

    7. If request messages handled by this client should always be forwarded to a specific device, , use fixed_server_address to set the device's Modbus address:
      (config service modbus_gateway client test_modbus_client)> fixed_server_address value
(config service modbus_gateway client test_modbus_client)>

      Leave at the default setting of 0 to allow messages that match the Modbus address filter to be forwarded to devices based on the Modbuss address in the message.

    8. To adjust the Modbus server address downward by the specified value prior to delivering the message, use adjust_server_address:
      (config service modbus_gateway client test_modbus_client)> adjust_server_address value
(config service modbus_gateway client test_modbus_client)>

      where value is an integer from 0 to 255. Leave at the default setting of 0 to not adjust the server address.

      If a packet contains a Modbus server address above the amount entered here, the address will be adjusted downward by this amount before the packet is delivered. This allows you to configure clients on the gateway that will forward messages to remote devices with the same Modbus address on different buses. For example, if there are two devices on two different buses that have the same Modbus address of 10, you can create two clients on the gateway:

      • Client one:
        • filter set to 10.

        This will configure the gateway to deliver all messages that have the Modbus server address of 10 to this device.

      • Client two:
        • filter set to 20.
        • adjust_server_address set to 10.

        This will configure the gateway to deliver all messages that have the Modbus server address address of 20 to the device with address 10.

    9. Repeat the above instructions for additional clients.
  6. Save the configuration and apply the change.
    (config)> save
Configuration saved.
>
  7. Type exit to exit the Admin CLI.

    Depending on your device configuration, you may be presented with an Access selection menu. Type quit to disconnect from the device.