s5 115 cpu 943b

it is not possible to modify the program in the cpu with eprom.Because it is not possible to erase the eprom electrically and I try to modify the program in the ram with unplugging the eprom but it also sees the the ram as eprom .So it is not possible to modify the program when cpu is without the eprom also.

any suggestion please.

thanks

In the S5-115U series the EPROM module is memory extension, not memory backup. You cannot change the parts of the program which reside in the EPROM. Only the parts residing in the RAM part of the memory can be changed on-line. Therefor, most programmers only store DBs in the RAM and keep the program in the EPROM.

The only way to change the program in the EPROM is to transfer it to disk, change it and burn the EPROM again.


Kind regards,

It depends on how big the program is, if you have a copy on disk (if not copy it to disk although you will not have any comments), remove the eprom & with a bit of luck it will fit in the ram, make sure you have a backup battery so as to retain the memory, you could now modify the program & run it in the plc ram.

Sometimes the program is too large however I came across this problem once & with a bit of slick re-design of the code I managed to fit it in the ram, however one large function block I needed to work on was too large to download without deleting all then re-loading it again (when a block is overwritten, it does not actualy overrite but loads the new block in spare memory, deletes the header of the old one & points to the location of the new block, then a compression is required to remove the redundant blocks.

I also tried to modify the program after unplug the eprom but it does not work .It still gives the same warning like before ( pb.. in the eprom ) and when I approv that nothing changes.It seems the memory as eprom even without eprom.

By the way when I look the istack it still ASPNEP is marked.

thanks

You may need to remove battery, delete the plc memory completely, remove eprom, re-boot with cold start before the aspnep (memorymodule is eprom) will clear, then re-load the program.

I know that without a complete clearout, & reset + download that some parameters are left, I suggest you remove the battery first as well before doing a delete.
I do remember on the S95U when new you had to do a reset + cold start before placing the battery or it would not go into run mode, the battery was placed while in run with no program loaded.