SLC/504 logic protection w/eeprom

Just installed my first AB panel... much thanks to those who assisted.

Anyway, the customer was aware of the proprietary nature of my code and the fact that the oem protect bit S:1/14 would be set and that I would not give him a copy of the code. He understands the situation but has a concern of the SLC losing memory and being without the machine until I can get back and reload... I don't like my customer being down either. So, here's my question. If I install the eeprom, Set bit S:1/12 (load and run), set bit S:2/9 (program compare, and set bit S:1/14 (oem protect) would this configuration;

A. Allow the plc to recover from loss of battery, memory corruption? (suspect yes answer).

B. Allow the customer to replace the CPU with virgin plc, install eeprom, powerup and resume operation w/no other steps? Don't know on this one because I don't know if all configuration data is on eeprom.

C. Prevent copying of my code? I understand the eeprom can always be installed in a different PLC, but, would the first machine still run since the eeprom wouldn't be installed and S:1/12 is set.

D. Any other ideas on how to protect my code and the customer in the event of failed CPU or loss of memory?

Thanks,
Jim

A: yes

B: yes, as long as it is the same CPU, OS and Firmware level

C: If the OEM lock is in place, it would be on the EEPROM as well. As far as I know, the only way around the OEM lock is to fill out a form letter that A-B has and it has to be signed by the OEM and they verify thru the OEM.

D: Unless someone else knows anything additional, it sound like you've got your bases covered.

About C:
Actually with S:1/12 set your program COULD be copied just by moving the EPROM to another CPU.
Here is from the help file:
"When S:1/12 is set in the status file of the user program in RAM, it does not require the presence of the memory module to enter the REM Run or REM Test mode."
In other words, the program can continue to run in the CPU even without the EPROM.

Also, I think that with S:1/12 the program including datafiles will be oveerwritten with each powercycle.
Maybe you dont want that various settings must be re-entered just because there has been a power cycle.

If you use S:1/10 in stead of S:1/12, then the EPROM must be inserted for the program to run.
And, the program will only be loaded in case of a memory error.

Jesper, I think you're correct. The help file states.

"You can use this bit to transfer a memory module program to the processor in the event that a processor memory error is detected at power up. A memory error means the processor cannot run the program in the RAM because the program has been corrupted, as detected by a parity or checksum error. This type of error is caused by battery or capacitor drain, noise, or a power problem."

"When S:1/10 is set in the status file of the user program in RAM memory, the memory module must be installed at all times to enter REM Run or REM Test modes."

1. In the case of the original CPU failing and the customer installing a replacement CPU, would the program upload? It seems it would only upload if there was a memory error.

2. Also, would S:1/10 have to be set in the replacement CPU (RAM) or just the memory module?

3. Will S:1/10 be set in RAM upon eeprom upload?

4. If S:1/10 is set in RAM and S:1/14 (OEM lock) is set would it be possible to go online and change S:1/10 in RAM thereby allowing run without eeprom present?

Thanks,
Jim

Jimpad.

1. The program will load, pending that CPU type, OS and Firmware versions matches (*).
A fresh CPU without any program in it will be be considered a memory error.
If there is a program in the CPU allready, then it has to be cleared. That involves removing the backup battery and shorting the prominent green capacitor for one minute.

2. S:1/10 has to be set on the memory module.

3. Everything will be copied to the CPU. Including all system status settings.

4. That would be a sneaky way to circumvent your "copy protection".
Not sure if it is even possible.
But you can make absolutely sure that the customer cannot trick you out, by programming an unconditional OTL S:1/10 in the program.

edit:
*: For this reason, AB ships replacement CPUs with a particular OS and Firmware version specified by the customer.

Jesper,

I cleared S:1/10 with S:1/14 set, so the OTL S:1/10 rung is necessary.

Help file states:

"When S:1/10 is set in the status file of the user program in RAM memory, the memory module must be installed at all times to enter REM Run or REM Test modes."

I know it says "the memory module" but does this really mean "THE" memory module or just "A" memory module? Obviously the concern here is that someone could upload the cpu, change the eeprom, and use the original eeprom in another machine.

If the customer has a spare CPU on the shelf, would he be able to download the OS and firmware to match the eeprom or would he have to have a CPU w/same OS and firmware as a spare?

Jim

I know it says "the memory module" but does this really mean "THE" memory module or just "A" memory module? Obviously the concern here is that someone could upload the cpu, change the eeprom, and use the original eeprom in another machine.

Click to expand...

You will have to experiment to know for sure.
But really, no customer would be THAT sneaky to try and bypass your copy protection scheme.

OS and Firmware will have to match.
I know that you can upgrade OS and Firmware (have done that), but I dont know if you can downgrade.