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MAC Addresses
It is recommended that you use the default MAC address given by the factory, however, you may override that default with a MAC address of your own choosing via the Logicmaster 90 Module Configuration screen for the Ethernet module.
Each byte of the MAC Address is an
Byte |
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| ________ _________ _________ _________ _________ _________ | |||||||||||
Hex | 0 | 8 | 0 | 0 | 1 | 9 | 0 | 0 | 5 | 3 | 1 | 2 |
Binary | 0000 | 1000 | 0000 | 0000 | 0001 | 1001 | 0000 | 0000 | 0101 | 0011 | 0001 | 0010 |
Another characteristic that is important, especially for
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 | 0 | 5 | 3 | 1 | 2 |
Binary | 0000 | 1000 | 0000 | 0000 | 0001 | 1001 | 0000 | 0000 | 0101 | 0011 | 0001 | 0010 |
Bit Order 8765 | 4321 |
| ...9 |
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| MSB of | the MAC | |||
LSB of the MAC | transmitted | |||||||||||
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If you assign your own MAC Addresses, there are 2 bits of the
HBit 1 in Byte 1 must always be a 0 to indicate an individual station rather than a Group address.
HBit 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).
HAll 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 |
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| MSB of the | ||
LSB of the MAC |
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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.
TCP/IP Ethernet Communications User's Manual ± January 1996 |
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