How to change the IP address of a Siemens PLC

[Arhitrav]

It might seem like a stupid question but please let me elaborate.

I had a PLC that already had some IP address on it which I needed to change. My initial thought was to just make a hardware configuration with the new IP address and download it to the PLC.
What I though was - When I download the new hardware config I'm telling the PLC "this is your new IP address"

A much more experienced friend of mine said I can't do this, because I won't be able to download the hardware config since the IP address I set there is not the same like the actual IP address of the PLC. He claims the IP address in the HW config is saying "download the HW config on this IP address".
So his solution is to install a new CP, give it some IP address, and then download the HW config from there.

Please tell me who is right? Probably it's him, but I find it hard to believe there is no simpler way to do this. What if you don't have a spare CP? It seems logical that you should be able to tell the computer both information, "connect to this IP address and change it to that IP address". Like you would do with proneta.

 

[AlfredoQuintero]

Welcome to the PLCTalk Net forum.

The I address of the PLC can be changed with the TIA portal. Just keep in mind two things:

1) In the program with the new IP address for the Siemens PLC, use the same device name for the PLC.
2) If the IP address is in a different subnet, the Windows workstation must have configured two IP addresses, for both the old and the new subnets. Alternatively, you can have two network interface cards (NIC), configured one for each subnet.

 

[Arhitrav]

Welcome to the PLCTalk Net forum.

The I address of the PLC can be changed with the TIA portal. Just keep in mind two things:

1) In the program with the new IP address for the Siemens PLC, use the same device name for the PLC.
2) If the IP address is in a different subnet, the Windows workstation must have configured two IP addresses, for both the old and the new subnets. Alternatively, you can have two network interface cards (NIC), configured one for each subnet.

Hi, thanks for you answer. I forgot to mention that we are using step 7 and not TIA portal

 

[AlfredoQuintero]

OK, so I am not 100% with Step 7, but I guess it should be the same. Let's hope the real Siemens experts see this post so that you get more accurate information.

 

[JesperMP]

With STEP7 Classic you can download a hw config (with the new IP address) to a PLC that already has a HW configuration.

When downloading the HW config, STEP7 will try to connect to the IP address of the PLC in the offline project. At this stage, simply overwrite the IP address in the download dialog with the IP address of the existing PLC. The PC must have an IP in the same subnet as the existing PLCs. Then perform the HW download.

When the CPU starts after the HW download, the new IP is active. This may mean that STEP7 cannot reach the CPU if the subnet has changed. Simply change the PCs IP to be in the same subnet as the PLC after the hardware download. You can then go online as normal.

 

[mk42]

A much more experienced friend of mine said I can't do this, because I won't be able to download the hardware config since the IP address I set there is not the same like the actual IP address of the PLC. He claims the IP address in the HW config is saying "download the HW config on this IP address".
So his solution is to install a new CP, give it some IP address, and then download the HW config from there.

Please tell me who is right? Probably it's him, but I find it hard to believe there is no simpler way to do this. What if you don't have a spare CP? It seems logical that you should be able to tell the computer both information, "connect to this IP address and change it to that IP address". Like you would do with proneta.

Others have told you how to do it, but I didn't see anyone else explicitly say that pretty much you are right and your friend is wrong.


Also, you can use a tool like Proneta to change the IP of a PLC before it has a project, but once the PLC has a project loaded, it takes the IP from that project.

 

[JRW]

Or download via the mpi or dp port and none of this is an issue

 

[AlfredoQuintero]

Also, you can use a tool like Proneta to change the IP of a PLC before it has a project, but once the PLC has a project loaded, it takes the IP from that project.

mk42, I had never done that for a PLC and so I tried it. Here's what I have found. Tested with both PRONETA and Profinet Commander.
Firts if all, the PLC must be in STOP mode for the IP address to change, otherwise the PLC responds with BlockError: SET not possible by local reasons (5).
In STOP mode the IP address changes, but at least as far as my test shows (and I may be doing something incorrect in which case please teach me), after power cycling the PLC the IP address reverts to the IP settings prior to the change done with the PRONETA/Profinet Commander. It seems that in order to change the IP address permanently changing the program is necessary.

 

[mk42]

Good test! I'm assuming that's the behavior with a project? It may vary a little bit from PLC to PLC model, not sure if 300 in Simatic Manager is different from 1200 in Portal (or if 1200 and 1500 are the same).



I will note that there is an option to "assign IP by other method" or something similar, which then means the project doesn't include an IP in the HW config, and you can change it via Proneta or system instructions in the project, or a couple other methods. I don't recall if this was around in the Simatic Manager days, or if it is a Portal only thing.

 

[AlfredoQuintero]

Good test! I'm assuming that's the behavior with a project? It may vary a little bit from PLC to PLC model, not sure if 300 in Simatic Manager is different from 1200 in Portal (or if 1200 and 1500 are the same).

I will note that there is an option to "assign IP by other method" or something similar, which then means the project doesn't include an IP in the HW config, and you can change it via Proneta or system instructions in the project, or a couple other methods. I don't recall if this was around in the Simatic Manager days, or if it is a Portal only thing.

Glad to know you find the test useful. I can see no "assign IP by other method" in TIA portal; neither for the S7-1200, and S7-1500 and even an S7-300 with a CP 343-1.
I do not have the Simatic 7 license so I can verify if that option can be used.

 

[JesperMP]

I can confirm that for S7 CPUs, if you set the IP with Proneta or Primary Setup Tool, the IP is only stored in RAM. It reverts to the old IP after a power cycle.
It can be useful still though. If for examply you cannot reach the S7 CPU in question from a remote connection because the Router has not been setup in the S7 CPU, then you can get in contact with the CPU in 2 steps:
1. Install Proneta or PST on a local PC. Use the local PC to temporarily update the IP with the Router information.
2. Connect to the S7 CPU remotely and set the updated IP permanenly by downloading an updated HW config.

There really is no problem with changing the IP on an existing S7 CPU. See what I wrote. You dont need to go online via MPI. For example the IM151-8 does not have MPI, only Ethernet so that is the only way.

 

[AlfredoQuintero]

Thanks Jesper for your comments, as usual useful and easy to understand.

 

[Ken Moore]

Since this is a S7-300 and Step-7. Could you not use ISO to connect?

 

[JesperMP]

Since this is a S7-300 and Step-7. Could you not use ISO to connect?

If a CPU is new out of the box and hasn't been loaded with a HW configuration and thus no IP is set, then you can find it and load the HW configuration by its MAC address.
As soon as an IP address is active, you can only find it by the IP address.
But the above is my experience if the PG/PC interface is set to TCP/IP.
Maybe you can directly find it by the MAC address if the PG/PC interface is set to ISO.
And maybe there is a limitation with that the CPU or CP must be stated to support ISO protocol.

A little bit of testing should clear that up. But I don't have the time to do that !

 

[Rob...]

If the module already has an IP address, you can go to online access, find the device you want. Then online/diagnostics and there's a tab to change IP address/profinet name. This is in TIA.

There's a similar method in step 7 classic.