Simatic TI 545 not scanning ladder logic

I have a TI545 PLC communicating over Profibus to a AB ControlLogix PLC (for anyone who read my last post, the Profibus cable was wired incorrectly).
The comms are definitely working as I can manually write values into the output words of each PLC and see the input in the other PLC.
However, the ladder logic in the TI does not appear to be getting scanned. It definitely was working yesterday when I was first testing as I was just copying the input word into the output word to check comms easily. At some point though, it stopped scanning - even the 'Always On' bit which was already existing in the code is off. This is the case even if I download the original code.
Anyone got any ideas? Massive newbie to TI's, but can't see what could be wrong. PLC is definitely in RUN mode - Loop mode is in RUN, Ladder mode is in RUN. Have tried power cycling, using the Power Up Restart, Partial Restart and Complete Restart options available in the PLC Operations window.
PLC isn't faulted (beyond a minor loop overrun fault), and running the diagnostics tool shows that everything is normal.

Hello

Did you also check if your ladder network 1 is executing?
If this is executing normal then it could be that parts of your program aren’t executing because of skip/label instructions or parts of your program are between MCR relays.


So my advice would be take a look at the first network in your ladder network.
If this networks is executing search through the program until you find the point where it isn’t executing perhaps of a label ,mcr or jump instruction.

Personally I don’t think it’s a fault in the processor but if the first network also isn’t executing then you could also try to disconnect power en disconnect the battery.
In this way you do a cold restart.
After that repower the CPU,reload the program and check if it’s executing.

Regards
Henny

How are you checking that the ladder is not executing ? Are you just looking at the code and not seeing the current status of any bits ? If you are using Workshop Software to access the PLC then check the menu option "Ladder Status" located under the "Diagnostics" heading. You said that even the alays on bit is OFF. Does it state OFF in a data window ?

Yep, you were correct Dua Anjing - had inadvertently turned off the Ladder Status display. I was also addressing the bits in my word incorrectly - I am accustomed to .0 being the LSB (have used mostly Rockwell) instead of .15