Upgrading PLC 5/25 to PLC 5/30. What to take good care of?

ckchew666

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Aug 2003
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Hi,

We've a job upgrading a critical plant (max. shutdown is 1 day) PLC 5/25 to PLC 5/30. There are a few units of PLC 5/25 to be upgrade, they are all network. Each of them are wired to a PV1200 on RIO. There are BTW/BTR, FAL, DTR & BSL/R instructions

I've not done any upgrade job for PLC 5 before, from what I understand, I just need to upload the program from the PLC 5/25 and download it into the new PLC 5/30 CPU.

Is there any configuration I need to take care? I think PLC 5/25 uses 57.6kbps for RIO only.

Thanks.
 
Last edited:
The only problems I've found in migrating from Classic PLC-5 to Enhanced PLC-5 have been with some local-rack block transfer modules that cannot keep up with the higher speeds of the Enhanced CPUs.

There's a "block transfer compatibility" bit in the PLC-5/30 status file that will slow down its backplane BT's if you encounter such a problem. I seem to recall it affected things like 1771-IXE thermocouple modules and maybe the IMC120 motion controller.

Otherwise, the Enhanced PLC-5 controllers execute the entire instruction set of the Classics, so you can just change the processor type in RSLogix 5, then go ahead and download.
 
There is another issue you should be looking at if you are using PID instructions:
if PID was not setup correctly i.e. trigger rate is not exactly equal to the loop update time, then switching to a faster processor will cause major process problems.
This issue has been discussed previously on this forum.
http://plctalk.net/qanda/showthread.php?t=11391
 
mrm37: No, i'm upgrading from classic platform to enhanced platform PLC 5/30. Not SLC 5/03.

Ken: Thx for your info. The bit you mentioned is S:26/05? I'm referring to the PLC 5 user manual as in attachment. If it's not the bit you mentioned, can you please highlight me?

Contr_Conn: I've browse thru the link given, it mentioned the problem only affect program with PID loops control by BSL/R (bit shiftting). I've browse thru the PLC5/25 program given by our customer, the special instructions are BTW/BTR, FAL, DTR & BSL/R. I don't see any PID instuctions inside. Due to my PID knowledge is not good, is there any possibilities that then the PID instruction in the PLC 5/25 is written in long method (like the BTR/BTW can be written in long method if we do not use the built in instructions)?

Thanks.
 

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