Use BootP DHCP to set an Allen-Bradley ControlLogix 1756-ENET IP Address

At Qualitrol International, we provide remanufactured Allen-Bradley PLCs, repairsfor Allen-Bradley PLCs, the Technical Service for Allen Bradley PLCs. Today we’re going to look at how to set an IP address on an Allen-BradleyControlLogix 1756 ENET Ethernet Module utilizing the BootP DHCP server software. Our Senior PLC Engineer will walk you through this process.
At the beginning, before you use the BootP software, power up your ControlLogix PAC rack. It will take a little bit of time before the PLC recognizes the PC internet connection. Once the connection has been established, then it’s okay to start the BootP server.
On the screen you’ll begin to see some data coming across, which shows the time that the message comes from the ENET module, the type of data that’s being transferred to BootP data packet, and then it also shows the Ethernet MAC ID. There’s no IP address assigned to the module at this time.
You’re making a direct connection to the module from the PC. There’s no switch or hub being used and because of that we’re using a crossover cable. If only direct cables are available, then a switch or a hub would be necessary to do what you’re doing.
If you have only one device on your network, you don’t have to worry about which MAC ID is the device that you’re looking for. Select any of the packets that have come across from the Ethernet module and then we click on “add to relation list”. At this point in time what you’ll do is change the IP address to
Click “okay” down at the bottom in the relation list you’ll see that the MAC ID has been associated now with the IP address that was just entered.
Now this is only temporary at this point. If you want to make this permanent so that the PLC will come up and power up with this IP address from this point forward, select the BootP in our new IP address and then click on “disable BootP DHCP”.
Notice down at the bottom that the BootP command has been successful, so the new IP address has been established in the Ethernet Module. The next time you power up the module, the new IP address will be in effect.


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