Hi,
I have taken over maintaining some HVAC units that are run by the Sysmac C20 PLC.
To keep a stock of PLCs handy we have had to buy used PLCs from Ebay.
The current PLCs are fitted with ROMs that I presume contain the ladder code in them. I have managed to just fit the OS and data ROMs into these 'new' PLCs and about 45% of the time they work.
To try to work out how it all works, I removed the ROM and cleared the RAM contents, using the programming module, so that I can write some basic testing code to test the PLCs and make sure the relays are good in the 'new' PLCs.
After playing around I cleared the RAM again, then replaced the original code ROM and set the DIP switches to the ROM setting. On switch on, the unit does not appear to be working, checking the code using the programming module I see no code.
To try and figure out whats going on, I removed the ROM from a working PLC and the unit still works, which I guess means the code is running in RAM.
I had assumed that setting the DIP switches would make the code run from ROM. Is there something I am missing?
Is there some action I need to do to get the ROM code copied into RAM?
The manual doesn't really expand on using ROMs.
All is talks about is saving/loading the code from tape, which I dont have, just ROMs.
I appreciate any help or suggestions.
Thanks.
I have taken over maintaining some HVAC units that are run by the Sysmac C20 PLC.
To keep a stock of PLCs handy we have had to buy used PLCs from Ebay.
The current PLCs are fitted with ROMs that I presume contain the ladder code in them. I have managed to just fit the OS and data ROMs into these 'new' PLCs and about 45% of the time they work.
To try to work out how it all works, I removed the ROM and cleared the RAM contents, using the programming module, so that I can write some basic testing code to test the PLCs and make sure the relays are good in the 'new' PLCs.
After playing around I cleared the RAM again, then replaced the original code ROM and set the DIP switches to the ROM setting. On switch on, the unit does not appear to be working, checking the code using the programming module I see no code.
To try and figure out whats going on, I removed the ROM from a working PLC and the unit still works, which I guess means the code is running in RAM.
I had assumed that setting the DIP switches would make the code run from ROM. Is there something I am missing?
Is there some action I need to do to get the ROM code copied into RAM?
The manual doesn't really expand on using ROMs.
All is talks about is saving/loading the code from tape, which I dont have, just ROMs.
I appreciate any help or suggestions.
Thanks.