Methods to set IP Addresses in an I/O device – Which is best?


As Industrial Ethernet Networks become more popular in automation applications, the question arises, what is the best method to set an IP Address in an I/O device?

Here are a few to consider:


DHCP allows a server to assign an IP Address to a device.  This is accomplished by tying the MAC ID of the device to the desired IP Address.  This is a simple way to assign an IP Address, simply plug the device into your Ethernet network.  The draw back is, who is in charge of the DHCP server?  What do you do if you have to swap out a device?  The replacement device will have a new MAC ID, so someone will have to assign the new MAC ID to the established IP Address.  Is this an IT or maintenance responsibility?

Proprietary Software:

This is self-explanatory, the plus with this method over DHCP is that most software packages will give you access to change the Subnet Mask and Gateway Address, as well as, the IP Address.  This method can be easily accomplished, but do you want to pull a laptop out just to swap a device?

Rotary Dials:

Now we are back to the DeviceNet and Profibus days.  The idea seems easy, but impractical.  Most Ethernet devices that have rotary dials usually have only 3 dials.  This allows someone to change the last octet of the IP Address, but you usually have to fall back to software to set the rest of the IP Address.

Displays and Pushbuttons:

This method is available in a few devices today.  An intelligent display can offer many benefits.  First, the entire IP Address can be set at the device.  Second, the Subnet Mask and Gateway Address can also be set.  Third, other features can be implemented into the display; errors can be displayed, MAC IDs can be displayed, software and firmware revisions can also be displayed.  By having full access to the IP Address, Subnet Mask, and Gateway Address this allows the closest device replacement methodology to the days of DeviceNet and Profibus.

Which is the best for you?  I will leave that for you to decide.  Please leave a comment on your method of choice.  If you’re interested in a display and pushbutton EtherNet/IP I/O device, check out our solutions.

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