Name resolution – FANUC Robotics America GFK-1541B User Manual
Page 185
ries 90™ PLC User's Manual
–
May 2002
GFK-1541B
6
Local Name Table Name Assignment
The second aspect involves building a name table that contains a mapping of symbolic names to
associated IP addresses. A name assigned in this table is also known as an alias. A network
address name assigned in the local name table can be resolved by Local Name Table Name
Resolution, as described in a following section. This table may be created as follows:
For the Series 90-70 Ethernet Interface (Type 2) and Series 90-30 CPU364, a name table
can only be created using the Windows-based PLC programming software (if supported).
For more information, refer to the chapter: “Ethernet Global Data”.
For the Series 90-30 Ethernet Interface, a name table can only be added, edited, and
deleted with the Station Manager command, CHNAMETBL. This command is documented in
GFK-1186, TCP/IP Ethernet Communications for the Series 90 PLC Station Manager
Manual.
DNS Name Assignment
The third aspect involves connecting and configuring a DNS (Domain Name System) name server
to the network. This DNS name server contains a database of name assignments and the
corresponding address information (IP address) for each of these names. This DNS name server
can be queried to acquire the IP address of a symbolic name known to that DNS name server. A
network address name assigned in a DNS name server can be resolved using DNS Name
Resolution, as described in a following section. Please ask your network administrator for more
information about the availability of a DNS name server on your network.
Name Resolution
Name resolution involves resolving a symbolic name (network address name) to its necessary
address information required for communication. Without name resolution functionality, a user is
required to know this addressing information (that is, IP address) to establish communication with
a remote device. Name resolution provides users a means to also use a symbolic name to reach
the remote destination.
For the purposes of this description, the client is the device which needs to resolve a symbolic
name. This symbolic name represents the IP address of the server. Possible clients include a user
of the Host Communications Drivers and users of the client capability on the Ethernet Interface
(for example, Channel API). Possible servers include the Ethernet Interface (for example, SRTP
Server) and the Host Communications Drivers (for example, unsolicited messages).
Name resolution of a symbolic name into an IP address follows a strict precedence rule as
follows: (The precedence order is configurable as an advanced parameter using the Station
Manager.)
1. Local Name Table
2. DDP
3. DNS
Each of these is described in more detail in the following sections.
Local Name Table Name Resolution
Local name table name resolution involves a simple table lookup to see if a mapping of the
symbolic name to its IP address information exists. Configuration of this table is described in the
topic “Local Name Table Name Assignment” earlier in this chapter.
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