Slc500 program loss

[OkiePC]

Joseph, I am sure that you know that the "Power Supply" button only provides an ESTIMATE, a guess, a rough guide. In many cases, it is a very poor estimate, either too low or too high, depending on how much external power is connected to the I/O modules.

The RSLogix500 estimator is on the money as far as I know. It can't, however, "know" that you have blue wires hooked up to the power supply output feeding voltage to other devices including analog modules.

That is when you need to add those external loads to the RSLogix500 calculation as Lancie suggests.

 

[Lancie1]

It can't, however, "know" that you have blue wires hooked up to the power supply output feeding voltage to other devices including analog modules.

Or vice-versa in my present case, having blue wires feeding external 24 VDC power INTO the analog output modules. The ESTIMATE is showing that I am severely overloaded, but I know differently. So far it is running...

 

[OkiePC]

Or vice-versa in my present case, having blue wires feeding external 24 VDC power INTO the analog output modules. The ESTIMATE is showing that I am severely overloaded, but I know differently. So far it is running...

Yes, I said that wrong earlier. It assumes you are using backplane power for analog outs where it's optional. Thanks, Lancie for the clarification.

 

[yasirkhi]

slc/05

Thanks for your support

PLC is monitoring safety. However light curtain, back door and front doors are hardwired.
Here is what I will check, correct me if I miss something

• PLC grounding
• I/O memory
• Turn only PLC off to check to see loose the program
• Replace power supply, if nothing works

 

[OkiePC]

I would change the order:

• PLC grounding (10 AWG green wire on the chassis mounting tab for earth ground and 14awg on the power supply for safety ground)
• Turn only PLC off to verify that it loses the program
• Replace power supply
• Add power filter
• If the above fails to help, install EEPROM and configure accordingly.

I don't know what you mean by "I/O memory" so I left it off the list. It is possible for a bad card to cause the SLC to fault, but I have yet to see a bad I/O card cause SLC memory loss.

It is also possible however rare to have a battery connection problem but that should also be associated with a warning bit and LED.

 

[Lancie1]

Main power [is] shut off, [then I] kill the power of robot and PLC. There is error- led blinks after I turn on the main power. So I download the program every time.

Yasir, I have not seen where you tell us which LED is blinking, or if the PLC has really lost its program, or if you are simply clearing a Fault by loading a new copy of the program. A fault (which causes a blinking red LED) can be caused by many other things besides loss of your program from PLC memory.

Try this: When the next "blinking LED" occurs, before loading the program, first go online and see if there is still a program in the PLC memory. If not, you will see the one-rung default program with the END statement.

On the other hand, if your program is still there, but you have a Fault due to program logic, then we can help you find it.

It is possible for a bad card to cause the SLC to fault, but I have yet to see a bad I/O card cause SLC memory loss

Paul, I agree, but I am not yet sure that Yasir HAS memory loss.

 

[joseph_e2]

I'm with Lancie on this one. On further review, I'm not 100% sure we are dealing with program loss. Seeing the results of going online while it's faulted may tell us much.

 

[yasirkhi]

I tried to turned the PLC power supply and problem still there. Since I can't hold the cell for a longer time, I will replace the PLC power supply on weekend or when cell is not running and get back here.

Thanks for your support

 

[yasirkhi]

Surely I will check if it is really a program loss or not.
Today I tried turning the power off only PLC to see if any external influence by main shut off.
But once your turn on the PLC fault blinks all the time, and you can not got online. I tried uploading and it stuck. However, when I try downloading on program mode, it goes smooth and does the job. And fault goes away.

I will 100% check again and emphasis what LANCIE is saying. Hopefully I will find the cell free in this weekend and try.

 

[Lancie1]

Today I tried turning the power off only PLC to see if any external influence by main shut off. But once your turn on the PLC fault blinks all the time, and you can not got online.

Yasir, here are some more things to check:
1. Each time you turn on power to PLC, go online with RSLogix, and from the left tree menu, got to "Processor Status, Errors, and read the values saved in S:20 and S:21 (which show the File and Rung that was executing when the last fault occurred. If this is the same File and Rung every time, it could mean a fault error is being generated by that rung in the program.

2. Even though you replaced the battery, check bit S:5/11 to make sure the new battery is actually charged up (or that the SLC 5/05 thinks it is). The SLCs also have capacitors that save a charge for 30 days. If this capacitor fails, it can cause memory loss problems.

3. Consider setting the Status File bit S;1/8 to reset fault on powering up the PLC.

Fault Override at Powerup S:1/8
When set, this bit causes the controller to clear the Major Error Halted bit S:1/13 and Minor error bits S:5/0 to S:5/7 on power up if the processor had previously been in the REM Run mode and had faulted. The controller than attempts to enter the REM Run mode. Set this bit offline only.

4. Look at Status File bit S:5/8. If this bit is set, the processor is trying to load a program from a memory module. In which case, you need to have a memory module installed in the processor, with a good copy of your running program installed in the memory module. If all else fails, consider adding a memory module, and setting one of the auto-load bits at "Processor Status, Mem Module". You could set S:1/10 so that when a fault occurs, and the processor is in "Fault" mode, then when you power on, a new copy of your PLC program is loaded from your new memory module.

 

[yasirkhi]

Thanks Lancie.
I will check this tomorrow and surely get back with results.

 

[OkiePC]

When you cannot go online with the SLC, does its name appear in RSLinx as "DEFAULT"?
That is the out of the box processor name and is an indication that the program is indeed gone, but only if you know the project you downloaded used something different.

Most people make the processor name the same as the machine name/number or nickname. If your project (look under controller properties) has "DEFAULT" for the processor name, change it to something else and save it before the next time you download.

Is that different than the processor name in your downloaded file?

 

[yasirkhi]

Problem solved

Thanks to all of you, who helped me fix the problem.

I changed the power supply and downloaded the program. And it worked fine.

Regards,
Yasir

 

[OkiePC]

Thanks for the feedback. I think that probably makes about 70% of my experience, plus reports of others for SLCs power supplies being the culprit for this symptom after confirming the battery and memory module config.

The Micrologix line is more sensitive to noise, but I have never needed to filter a SLC even in some very trashy (VFD and DC drive noise) areas.

With good grounding I still have occasional problems with the Micro's, especially the snap together expandable versions wiping themselves due to hard bus faults. Those are the only models I like to fit with EEPROMs and configure the error bits to prevent having to use RSLogix to restore them when there is some other problem. The drawback, is living with your data tables getting reset, but that can be overcome with alarming and HMI backup of that stuff.