sigmadelta

Unfortunately, there is no information about the pin configuration that I can find. I found a non-working IM 621 on ebay with the cable for 10 euro (plus shipping): https://www.ebay.co.uk/itm/Siemens-Simatic-S7-6ES7-621-1AD00-6AE3-993gr-RA-2-9kg/153546712587?hash=item23c018e60b:g:aNcAAOSwPdNdF0Q1 I would consider upgrading this C7-621 to a S7-1500 and Comfort HMI if you plan to keep this machine for a long time.

If you have the unit and want to find out what version it is, open Accessible Notes (3rd icon from the left in SIMATIC Manager), then right click the node that shows up (typically node = 2) and choose PLC -> Module Information

V1.1 and V1.2 are firmware (operating system) versions of the C7-621. If you have the unit, you can see the firmware version online.  If you don't have it, and don't know the firmware version, choose V1.1.  You can always replace it with V1.2 later if you find out it is V1.2.

Try this page for information about the OP320-A: https://plc.home.blog/2018/08/24/op320-a-software-download/

This may help too... but verify the NCU/PCU you have first!! https://support.industry.siemens.com/tf//WW/en/posts/restore-the-archive-of-840d-pl/206856?page=0&pageSize=10

This might get you pointed in the right direction... now I remember I restored from an archive that was stored on the HMI (or PCU?) that was connected to the NCU... but this was a different 840D, and I'm not sure which NCU/PCU you have in your system. http://www.plctalk.net/qanda/showthread.php?t=59436

Upon further reading.... The NCU itself sits inside the box. So we still don't know which NCU you have.

Don't you have a computer attached to the system?  What software is running on it?

Note: I am not a Sinumerik expert, I'm only trying to point you in the right direction. I believe this might be what you want, especially chapter 12.4.2.  Unfortunately, I did this only once about 20 years ago, so I don't remember exactly the steps I did. https://support.industry.siemens.com/cs/document/28518260/nck-plc-drive?dti=0&lc=en-WW

First, in order for anyone to help, we need the part number(s) of what you have, and if there is an NCU version printed on your NCU BOX, to either write it, or even better, take a picture of it.

Here is a link to the cable pinouts for TI 305 PLCs: https://cdn.automationdirect.com/static/specs/directsoftcables.pdf Use D3-DSCBL-1 Also you can use either TISOFT 305 or Directsoft from Automation Direct to program the CPU.

It's easier to find if you go online with Siemens STEP 7 software, or VIPA WinPLC7 software, and look at the diagnostic buffer of the CPU.

I sent you a private message.

Another thing that it might be, is the files are read-only.  Find the Step 7 project folder which is in C:\Program Files\Siemens\Step7\s7proj\ and right-click on it an click Properties... uncheck the Read-Only checkbox, and if it asks, apply the changes to all files and folders.

Try right-clicking your HMI in the TIA Portal Project then Compile -> Software (rebuild all).  Save the project, then download.