Assigning a 1756-ENBT with an IP Address

Join Date
Oct 2004
Posts
51
Hello,


I have a simple question for those of you who are more familiar than myself with ControlLogix.

I have purchased an AB 1756-ENBT/A EtherNET/IP card. Now obviously the card does not currently have an IP address assigned to it, only a MAC address.

Now I have been led to believe that I should use the BootP program to give the card an IP, however having tried this I have found that the BootP program acts as some sort of server which needs to be permanently connected. If it is not then the card loses its IP when power is removed from it.

Can anyone provide me with the instructions to manually enter the IP address on the card?

Thanks
 
After adding the module to your controller's I/O configuration, the module properties tab should open. Enter the module I.P. her and when you finish configuring the module, you download the ladder file.
 
I think RSLinx comes with a BootP server. Or maybe it's RSLogix 5000. On my laptop it is on the Start>Programs>Rockwell Software>BootP-DHCP Server menu. I use this to assign an IP address to the card, then set up RSLinx to find the card, then right click on the ENBT and go to module configuration to disable bootP and assign a permanent IP address.
 
BOOTP assigns a temporary address to ENBT.
One it is done, connect with RSLinx, Go to Module configuration and set IP as a static. It will stay in this case.

BOOTP server comes with RSLinx installation.

After adding the module to your controller's I/O configuration, the module properties tab should open. Enter the module I.P. her and when you finish configuring the module, you download the ladder file.
It is a common mistake to assign IP in the project.
ENBT as any other communication module should be in I/O configuration ONLY if it controls I/O or does Produced/Consumed (consumer side only)

Rockwell has multiple knowledge base documents about this.
Do not put ENBT in I/O tree if it used for messaging, HMI or data collection!
 
Another way of doing this is to open Linx find the module and right-click on it. You can then choose the configure module option to set the IP address. Just remember if the module is part of your project in the I/O tree, you must stop Linx before trying to configure the module in the project. There is some communication conflict between Logix and Linx during the configuration that will cause you some grief.
 
Another way of doing this is to open Linx find the module and right-click on it.
This is possible only if IP address already assigned to ENBT or you have another communication module in the same chassis. Sometimes ENBT is the only comm device and BOOTP is the only way to do this initially.

you must stop Linx before trying to configure the module in the project. There is some communication conflict between Logix and Linx during the configuration that will cause you some grief.
How you will load project if you stop RSlinx? I never heard about this.
Setting IP is the I/O tree is incorrect way of doing this
 
Last edited:
I am new to the ControlLogix platform, so you guys probably have much more experience than I. My project had consumed tags, therefore, I understood you had to add the module to the I/O tree.

To clarify what I meant by turning Linx off. I added my module to the I/O tree, loaded my project, then closed Logix.

Opened Linx, and found the ENBT module using the DF1 driver through the processors channel 0 port. Right-clicked on the module, selected configure module and entered my IP information. I then cycled the power to the ENBT to reboot it.

I then closed and shutdown Linx. Next I opened Logix (it opened Linx) and went on-line with the processor and completed configuration of the module.

I understand this my not be the best way of doing this but, it did work. The problems with configuring the module I experienced at first, I believe, were due to having opened Linx first and initiating a session with the module, then opening Logix and trying to communicate with the module in "configuration" mode.

I am a newcomer to this site, and see that I have much to learn about AB. I appreciate the dialog and thanks for your help.
 
Joe,

The procedure you described is how I usually assign an IP address. I connect to the processor with a DF1 driver and then use RSLinx to configure an IP address.

However, opening and closing RSLogix and RSLinx as you describe is not necessary. If you were having a probelm my guess it is not related to opening and closing Logix and Linx.

OG
 
Zombie thread!!

Curious as to what wipes out the dynamic IP address? If comms, are interrupted for a prolonged time period does this wipe the dynamic IP address out?
 
Zombie thread!!
Shotgun to the forehead.
I hate the undead.đź’€
Should have just started a new thread since this has very little to do with the original.

Curious as to what wipes out the dynamic IP address? If comms, are interrupted for a prolonged time period does this wipe the dynamic IP address out?
A DHCP server assigns each device an IP address for a limited period of time, called a lease. When that time is up the device renews the lease and is typically assigned the same IP address. Leases can vary from a few hours to days. This period is determined by the configuration of the DHCP server. If the lease expires and it can't renew (communications interrupted for example) it will lose that IP address. When it does finally obtain an address from the server it may or may not be the same IP address.

This is why it is important (in a control system environment) to set up persistent leases so the same device (as determined by MAC address) is always assigned the same IP address.
 
Hello,


I have a simple question for those of you who are more familiar than myself with ControlLogix.

I have purchased an AB 1756-ENBT/A EtherNET/IP card. Now obviously the card does not currently have an IP address assigned to it, only a MAC address.

Now I have been led to believe that I should use the BootP program to give the card an IP, however having tried this I have found that the BootP program acts as some sort of server which needs to be permanently connected. If it is not then the card loses its IP when power is removed from it.

Can anyone provide me with the instructions to manually enter the IP address on the card?

Thanks

gareth, by far the simplest way to configure an Ethernet module is to put it into an empty slot in a chassis, and just browse to it with RSLinx, across the backplane, using any comms method you already have to that chassis, and if you don't have any other comms modules, you can always go in via the processor's serial port.

Right-click the module when you have found it in the RSLinx browser tree, and choose Module Configuration (see 1st pic).

Then on the configuration window, choose Port Configuration tab. (See pic 2)

(1) Set the Network Configuration Type to Static.
(2) Set the IP Address
(3) Set the SubNet Mask
Set any other IP fields as required
(4) Set Auto-Negotiate

Click OK and the module is field ready. It will remember those settings.

Using BOOTP will not achieve this, although there is an option in BOOTP to "Disable BOOTP" for a device (akin to setting Static mode above), but this optrion has to manually performed, it cannot be done automatically.

Because you can't "fix" the IP address automatically with BOOTP, the idea of having it as a server on the network to deliver IP addresses (Dynamic IP) raises maintenance issues.

Consider a failed ENBT is replaced by a maint. tech.... How will it get it's IP address? BOOTP won't do it, because it won't have an association of the new module's MAC address. So someone has to go into BOOTP to edit the association file. That file might be on a server he won't have access to.

An even worse scenario is that a suspect module is replaced with a module that was pulled from another area of the plant, and returned to stores. This module's MAC might well be left in the BOOTP association file, and it will then receive an inappropriate IP address.

IMHO BOOTP should not be used in an industrial setting where IP addresses must be fixed so that communications routing is guaranteed, although I know of places that use it as standard, and I always ensured the tech's were aware of the pitfalls mentioned.

2012-01-28_132649.jpg 2012-01-28_132841.jpg
 

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