RHC & TDF on 1747-L553 5/05 CPU-64K OS500

Hello,

I have a system that use to have a 1747-L542C 5/04 CPU -32K Mem. OS401 Series C FRN 3-8 and was upgraded to a 1747-L553 5/05 CPU - 64K Mem. OS500.

Since the upgrade, the system has been running for over 5 year without issues but recently, management has requested some changes. I uploaded the program and modified the codes. Upon verifying the project for downloading, all of the RHC and TDF instructions used in the program are flagged as the following errors:

ERROR:RHC instruction is not valid on the currently selected processor!-> 1747-L553 5/05 CPU - 64K Mem. OS500.

ERROR:TDF instruction is not valid on the currently selected processor!-> 1747-L553 5/05 CPU - 64K Mem. OS500.

Referring to the instruction set, these instruction can be used on SLC 5/03 OS302, SLC 5/04 OS401, and SLC 5/05 OS501 Series C processors. I have not had a chance to physically check and confirm the label on the processor, but logging on remotely and looking at the Controller Properties and I/O Config, the previous programmer was able to work around this limitation somehow.

Does anyone have experience with this issue or seen a work around? Any suggestions? Thanks.

K

Contacted Rockwell, they are stumped.

Tried creating a blank project with a 1747-L553 5/05 CPU - 64K Mem. OS500 processor and the the RHC and TDF are greyed out.

If I set the controller to a 1747-L553 5/05 CPU - 64K Mem. OS501 then the error clears, but now the processor is a mis-matched.

Anyone?