Mac addresses – FANUC Robotics America GFK-1541B User Manual
Page 187
ries 90™ PLC User's Manual
–
May 2002
GFK-1541B
6
MAC Addresses
Note
It is highly recommended that you use the unique default MAC supplied within
the Ethernet Interface. However, you may override that default with a MAC
address of your own choosing with the Station Manager CHPARM MACADDR
command (See GFK-1186, TCP/IP Ethernet Communications for the Series 90
PLC
Station Manager Manual.)
The MAC address is a 48-bit binary number that identifies the station on the physical network.
The MAC address is typically expressed as a 12-digit hexadecimal number. A typical MAC
address is represented as follows:
Byte 1 2 3 4 5 6
________ _________ _________ _________ _________ _________
Hex 0 8 0 0 1 9 0 1 5 3 1 2
Binary 0000 1000 0000 0000 0001 1001 0000 0001 0101 0011 0001 0010
Another characteristic that is important, especially for multi-vendor networks, is the order of
address-bit transmission on the physical medium. MAC addresses are transmitted in ascending
byte order, with the least significant bit of each byte transmitted first.
The example above is shown including bit transmission order as follows:
Byte 1 2 3 4 5 6
________ _________ _________ _________ _________ _________
Hex 0 8 0 0 1 9 0 1 5 3 1 2
Binary 0000 1000 0000 0000 0001 1001 0000 0001 0101 0011 0001 0010
Bit Order 8765 4321 ...9 |
| MSB of the MAC
LSB of the MAC address-first bit transmitted address-last bit
transmitted
If you assign your own MAC addresses, there are 2 bits of the 48-bit address that you must set
according to the instructions that follow:
Bit 1 in Byte 1 must always be a 0 to indicate an individual station rather than a Group
address.
Bit 2 in Byte 1 must be a 1 to indicate that the address is locally administered. (In the typical
default MAC address shown above, bit 2 in Byte 1 is a 0 indicating that it is a globally
administered address).
All other bits can be set as desired as long as all stations on the network have unique
addresses.
An example of a locally administered MAC address is shown below.
Byte 1 2 3 4 5 6
________ _________ _________ _________ _________ _________
Hex 0 2 0 0 0 0 0 0 0 1 0 0
Binary 0000 0010 0000 0000 0000 0000 0000 0000 0000 0001 0000 0000
Bit Order 8765 4321 ...9 |
| MSB of the
LSB of the MAC address-first bit transmitted MAC address-last
bit transmitted
If you must change the Station MAC address, check with the person administering your network
to make sure that you select an address that fits into your local administration scheme.
The document is for study only,if tort to your rights,please inform us,we will delete