SLC500 Conversion To CLX5000 'Unused Memory'

ian.smith7

Member
Join Date
Aug 2002
Location
UK
Posts
145
Hi All
I have just started a project to convert one of our machines from SLC500 to CLX5000. One of the first steps in the Rockwell guide was to run a 'Delete Unused Memory' Instruction on the SLC program. When I looked at the memory areas being deleted I found that some of it was actually referenced by devices on the network but not within the SLC500 CPU.
My solution is to create some rungs of code referencing memory above that which I need to keep, just a move instruction to a Garbage register.
my questions are
Is this 'Delete Unused Memory' step really required
Is there a better way to preserve these internally unreferenced memory areas?

cheers
ian
 
No, its not required; it may help conserve some memory in the conversion. But if it is like you describe, memory accessed by other devices, I would probably leave it alone if those devices are going to be re-directed to the same tags in the new CLX memory.
 
There is not a SLC out there that won’t fit in an L71 so I wouldn’t bother. I just got done converting a 553 with only 500 words of memory left and the L71 still had about 60% memory left.
 
Thanks for the reply,
Any other advice to pass on i am a little concerned about the IO Mapping.
If a 16 bit (INT) hardware input register is mapped to a 32 bit DINT and all 16 bits of the INT are on. Will the MOV instruction Take bit 16 of the INT and Map it to Bit 32 of the DINT Turning BIT 16 of the DINT OFF (Treating it as a negative number)? Should I use COPY instead?

Also where the SLC had a 32 Bit Input card It was contained in two consecutive INTs. After Conversion the hardware IO has 1 32 bit register but the soft IO has 2 Consecutive DINTs. To get round this I used a SWPB instruction for the High word exchanging the two Higher Bytes into the lower bytes of the destination Soft input DINT. Is that instruction OK to use Is there a Gotcha?

Cheers
Ian
 

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