X20 system modules • Bus controllers • X20BC0087
546
X20 system User's Manual 3.10
4.5.8.9 Automatic IP assignment by a DHCP server
If a network address switch setting between 0x80 and 0xEF is configured, the bus controller will attempt to request
an IP address from the DHCP server. To query this IP address, simply run a "ping" command with the hostname.
The bus controller registers this hostname on the DHCP server, which should forward it to a DNS server.
Example
The hostname (DNS name) is made up of three elements:
"br" + "mb" + address switch value (three decimal places).
This means, for example, that the following hostname is generated for address switch setting
0xD7 (dec. 215): "brmb215"
If the DNS service is not available on the network, the bus controller's two NetBIOS names can also be used for
access. The secondary NetBIOS name is identical to the hostname. If the address switches are set to 0x00, it is
identical to the primary NetBIOS name. The bus controller can only be reached via its NetBIOS name if no other
routers or gateways are in the way.
4.5.8.10 Changing the IP address with the network address switches
The address switches can be used to change the last byte in the IP address configured on the bus controller. The
IP address saved in flash memory is not changed. If the address switches are set to 0x00, the bus controller applies
the IP address last saved to flash memory. Switch positions between 0x01 and 0x7F cause the last position of the
IP address (the lowest byte) to be overwritten by the value of the address switch. This provides the user a quick
and easy way to address a large number of bus controllers. In short, an IP address between 192.168.100.1 and
192.168.100.127 can be selected for a bus controller using the address switches without requiring any additional
software configuration.
4.5.8.11 Information about NetBIOS names
In addition to the hostname used to register on the DHCP server, the bus controller also has so-called NetBIOS
names. These are used to access the bus controller from a PC using its name (as opposed to its IP address). This
is only possible if no routers or gateways are in the way, however.
The primary NetBIOS name is always composed of the prefix "br" and the MAC address from the bus controller
(see 4.5.8.9 "Automatic IP assignment by a DHCP server" on page 546).
The secondary NetBIOS name corresponds to the primary NetBIOS name at address switch position 0x00. This
is necessary because there may be several bus controllers with the address switch 0x00 in a network segment.
In this case, the IP address from flash memory is used.
For all other address switch positions, the secondary NetBIOS name is generated from the network address switch
value (as in DHCP mode): "br" + "mb" + address switch value (3 decimal places).
A hostname defined explicitly by the user will be used for the secondary NetBIOS name regardless of the address
switch value.
This makes it possible to access the bus controller with the NetBIOS name configured using the address switches.
This is also possible if the controller was not configured for use with a DHCP server (address switch setting between
0x01 and 0x7F).
4.5.8.12 Saving an IP address to flash memory
The IP parameters in flash memory can be changed via the Modbus protocol, the ModbusTCP Toolbox or the
Telnet interface. The ModbusTCP Toolbox can be downloaded from the B&R website.
The IP address, subnet and gateway are all defined in the address range 0x1003 to 0x100E. Each has a length
of 4 words. The data is applied by writing the constant 0xC1 to the address 0x1140 ("Write Single Register" fc6,
addr. 0x1140, data 0xC1). The new settings are applied after the bus controller is restarted.
Summary of Contents for X20 System
Page 2: ......
