You need RS232 cable. Description you can find here. https://www.br-automation.com/downloads_br_productcatalogue/BRP44400000000000000017742/3cp260601.pdf
With B&R, you can also store the source project on the PLC, but you must enable this option in the project, and this is usually not the case, because then your “know-how” can be easily reused. You can backup and restore, which is usually enough. If you have contact with the machine builder, he can send you the project (if he is open to that) and then you can do whatever you want.
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Oh my bad I didn’t see your previous message !
Thank you for your consultation. I apologize for the primitive questions. Now I’m just getting ready to somehow solve this issue, dealing with current issues … While I’m forming an idea of where to start and which side to approach … The manufacturer is unlikely to give the source code, they are not ready for a new project either … Either there are no programmers, or there are no source code … They suggest either trying to “fix” the old controller or buying a new line … ;-(
ср, 3 сент. 2025 г. в 16:38, Jaroslav Kovar via B&R Community <notifications@brcommunity.discoursemail.com>:
It is perfectly fine. The community is about discussion and helping each other. The bad thing is that you are speaking about a very old system, and if you do not have support from the manufacturer, it can be very difficult. If you think the problem is related to the CP260 itself, you can contact B&R repair at headquarters to ask if they can provide you with a spare part or repair this old PLC. I reviewed the history of this chat, and you mentioned that the problem of the CP260 not starting does not happen every time. So, for me, this could indicate that the problem is NOT in the PLC itself but somewhere in what is connected to it, maybe an IO card, communication card, or whatever. So this is something you might want to take a look at as well. If you connect using Automation Studio, the logger can provide you with very important details.
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Good day.
I’ll try to ask you so as not to break mine… 
We decided to remove the controller from the bus to check the state of the contacts and the general condition of the parts. But on the back bus, where all the modules are connected, we saw a board with a battery. The question is - won’t the program in the controller be erased if we disconnect it from the back bus? And how much time do we have if the program can be erased!?
Now the battery is 2.99V. Apparently it should be 3.6V?!
There are photos in the attachments.
Good day.
I’ll try to ask you so as not to break mine…
We decided to remove the controller from the bus to check the state of the contacts and the general condition of the parts. But on the back bus, where all the modules are connected, we saw a board with a battery. The question is - won’t the program in the controller be erased if we disconnect it from the back bus? And how much time do we have if the program can be erased!?
Now the battery is 2.99V. Apparently it should be 3.6V?!
https://drive.google.com/drive/folders/1J3Y5NJgRre5pPlt8HbEF2uTgclKRbG_b?usp=drive_link - photos
вт, 2 сент. 2025 г. в 11:50, Jaroslav Kovar via B&R Community <notifications@brcommunity.discoursemail.com>:
2.1.5 Changing the Lithium Battery The product design allows the battery to be changed with the PLC switched either on or off. In some countries, safety regulations do not allow batteries to be changed while the module is switched on. Therefore, B&R recommends the battery is switched when the power supply is switched off. Data is lost when modules do not have their own buffer.
Question! So when replacing this battery and/or disconnecting the controller from the back bus - will the program be erased? And in what time!?
How much should one be wary of losing software when replacing this battery?
Please clarify what does “the controller must be the same” mean!? Siemens may have the same controller, but with a different order number - and this requires changes to the project! BR’s controller simply has to be CP260 or do you also have options with different order numbers!?
In B&R type must be the same, so CP260. You can have different hw revision, but that is not the problem. B&R keep it backward compatible. If you will have different type of CPxxx, so not CP260, you have to change it in the project, compile and download new.
Program not. Program is stored on the FLASH. With battery, you backup RAM where the remnant values of variables are stored or maybe time, not sure how it is with this CPU. But this depends on your project, maybe remnant variables are not even used?