HELP !!Please Lost PLC COMM

richleva

Member
Join Date
Sep 2012
Location
ontario
Posts
79
Hello Everyone!
I'm in trouble here...
We have two PLCs on a network IP (192.168.1.43 node 51, 192.168.1.44 node 52).

I used the file and program from PLC 192.168.1.44 and uploaded it to (192.168.1.43 node 51). I made sure to change the ip in IO Configuration but after downloading to the PLC (192.168.1.43 node 51) I got a message saying the communication configuration are not the same do you and to apply and I said yes. So the download ended being unsuccessful to PLC 192.168.1.43 node 51) so I redownloaded the older file back into it, now its ok ....but I somehow lost comms with PLC (192.168.1.44 node 52) I tried downloading a different file but didn't work. I get error "No response from processor at selected path". And in RSLINX or RSWHO there's a big red X on the PLC, and Ping was also unsuccessful

I should also state that
I'm doing this remotely from a different site so I cant access the PLC physically.
Im Using RSlogix Micro. And Processor type Micrologix 1400 Series B.

Any information is appreciated
PLEASE HELP ME :(
 
If you can't PING the controllers and you aren't certain which addresses you really entered, then you're not going to be able to solve this entirely remotely.

The good news is that you can probably walk somebody on site through using the LCD screen to check on the IP address and cycle power to clear any sort o IP conflict that has been created.

The MicroLogix 1400 also allows setting of the IP address, subnet mask, and default gateway via the onboard LCD and keypad.

All the steps to do so are in the User Manual, in Chapter 5, starting on page 120.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1766-um001_-en-p.pdf
 
Is there anyone at the actual site who can lay eyes on your 1400 that ends in IP Address 52 ?(the one you are having problems with)

If there is have them go and look at the LED's on the front of the 1400 and just confirm that it is not faulted and that it is in run mode.

If it is not faulted and is in run mode, then have them look on the display and see if the IP address on the display matches the IP address you expect to see.
If it does not then you can have them manually put in the correct address.

If the person doing this is not savvy with Micrologix or PLC in general you may want to give them step by step instructions on how to do this.

Facetime or similar may be handy so you can see what they are seeing also.

Also since you are using Ethernet IP Addresses, what is the deal with the node #'s you refer too?

EDIT: Ken is faster.

BCS
 
Something’s not adding up. You are using RSLogix Micro starter lite with a MicroLogix 1400? That shouldn’t work. Micro starter lite only works with MicroLogix 1000’s and 1100’s.
 
Hi Bering, and thanks to every one for the help. I will contact the customer tomorrow morning and walk them through the the steps of changing the ip back to 44. Hopefully that's all it was !!! I will keep you guys posted.
Thanks again ...!!!
At this point there's not much I can do from here :(
 
Channel IP address v Path IP address...

This one made me laugh when I read it, but it's easy happen. :ROFLMAO:

You have to be very careful with controller paths in RSLogix 500. Especially when uploading and downloading to different controllers on the same subnet.

Here's what I think happened you...

You uploaded the program from 192.168.1.44 or opened a copy of it. This had a correct path to 192.168.1.44.

You changed the channel IP address in that program to 192.168.1.43, and saved the program.

You downloaded that program to what you thought was 192.168.1.43, but the live path in RSLogix 500 was still to 192.168.1.44.

So, you actually downloaded it to 192.168.1.44 with the channel set for 192.168.1.43.

It said there was a comms config difference, which there was, you proceeded with the download.

The 192.168.1.44 controller was now set to 192.168.1.43.

You now had two controllers set to 192.168.1.43.

You though the download was unsuccessful, it was successful, but to the wrong controller.

This created a duplicate address on the network and one would have been taken down.

You then opened the original program for 192.168.1.43. This had the path set to 192.168.1.43.

You downloaded this to whichever controller was still on the network at 192.168.1.43, but could now have been either of them.

You could not find 192.168.1.44 anymore because you had now changed it to 192.168.1.43.

You will only find 192.168.1.43 on the network at present, but which controller is live and which one has been taken down for duplicate is unknown.

Until someone changes the correct controller back to 192.168.1.44 for you, you will not be able to see it again.

I could be wrong in there somewhere. I just thought it out quickly, but it will be something close to the above that happened. Have whomever you rope in check both controllers for the same IP address.

The key here is that the IP address that you configure and save for the channel does not make RSLogix 500 download the saved program to that IP address. You must browse the live RSWho within RSLogix 500 to choose the correct controller that you want to download to. This can be a controller with the same IP address as the program, or a different IP address. If the current live path has a different IP address, you will get the warning for a difference in the configuration. To proceed overwrites the old IP address with the new.

When you changed the IP address for the channel to 192.168.1.43, in the original 192.168.1.44 program, you should then have browsed live to the path for the 192.168.1.43 controller and then downloaded. This would not have given you any warning, as the configured IP address for the channel and the current IP of the live controller matched.

Tricky stuff alright. My co-ordinator defaulted a MicroLogix 1400 in a machine last week with this confusion over paths and configurations. He also blew one up in the office for good measure (unrelated). He's wiring up a 1769-L16ER in a machine this week while I do the program. I can't wait for those fireworks!

Regards,
George
 
This one made me laugh when I read it, but it's easy happen. :ROFLMAO:

You have to be very careful with controller paths in RSLogix 500. Especially when uploading and downloading to different controllers on the same subnet.

This scenario is what prompted me to start using a different driver of the Ethernet Devices type for each customer I visit. I did not "hit" the wrong controller with a download (yet), but just figuring out what is what with a single Ethernet IP driver can make your head spin when you have populated one laptop with a hundred different PLCs from 14 different sites and all you have to go by is a CPU model number and IP address.

I give each customer its own Ethernet Devices driver and fill in the browse table with the relevant IP addresses.

Then, the controller names show up in RSWho and only those I want to see at any given time. Once you are online with the driver, perform a save, and update the project path to match your driver, it makes life easier the next time you open the file and go online, or do offline edits then need to just download them.

I am sure there are situations where the Ethernet IP driver is superior, and most of my customers are using SLC/Micrologix products so my method may not work best for other folks who deal with the newer, faster, smarter gear.
 
I try to do the same Paul. Have separate "Ethernet devices" drivers for different lines/machines/segments. Our addressing schema allows the fixed IP address of the laptop to access just about all devices remotely.

There is a limit to how many Ethernet devices drivers you can add in RSLinx, and I used to know it, but I'll be damned if I can remember the figure? I think it's 100, but I don't know why I think that? :unsure:

On the other hand, my memory served me well to remember this...

549521 - MicroLogix 1400 LCD displaying IP conflict
Access Level: TechConnect

An easy thing for the runner to quickly check when they first lay eyes on the controllers.

Regards,
George
 
Thanks Goespark !!
That's exactly what happened!! ..So you agree that having someone on site to change the IP back to 192.168.1.44 using the LCD display should fix the issue?

Great community on this forum!!
 
If they find an IP address conflict message on the LCD display then yes, they should only need to manually change the last octet from xxx.xxx.x.x3 back to xxx.xxx.x.x4, and cycle power to the controller to accept the change.

EDIT: Just make sure that the correct IP addresses are in the correct controllers when they are done and not mixed up. How ye know this I can't say. A sticker with the IP address is always very useful for walk up identification of addresses.

I'm also as curious as BCS is...

Where are you seeing or setting those node addresses 51 and 52 you've mentioned?

Regards,
George
 
Last edited:
51, 52 are just the processor node numbers under system configuration. And we shouldn't get the IP mixed up since there only two PLC in two different plants. And we know exactly which PLC needs "44"

But also, if both PLC have the same IP wouldn't they both fail? and not just the one
?
Appreciate your time !!
 
As the MicroLogix check every two minutes for a duplicate address, the first one to perform their check after the duplication will see the other IP and shut down the port. By the time the other one checks, the first one is gone and so it will plod along oblivious to the fact.

G.
 

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