Slc500 program loss

[yasirkhi]

Hi There,
I have slc500 with communication DH485. Controlling safety and HMI(panel view 550). Whenever we shut off the power of robot, it loose the program and fault led blinks, until download the program again, it doesn't go away.

Any help will be really appreciated.

Yasir

 

[joseph_e2]

Do you have a battery installed? Is it dead? The exact model will determine where and what type it takes.

 

[Lancie1]

Whenever we shut off the power of robot, it loose the program and fault led blinks,...

Yasir, When you shut off power to the robot, does that also shut off power to your PLC?

If so, then as Joseph said, you probably have a dead battery in your PLC and are loosing the program due to no power to keep it alive.

On the other hand, if the PLC still has AC power, then you probably just have a condition in your robot program that is causing a fault. You can reset a fault using the SLC programming software, but it will re-occur when you switch back to RUN mode. In this case, you need to search for the fault-causing logic and fix it.

 

[Mickey]

Or it's loading from a blank memory module ( EEPROM). Is there one installed?

If so make sure it has the latest program in it, or pull it out.

 

[yasirkhi]

Do you have a battery installed? Is it dead? The exact model will determine where and what type it takes.

Installed a brand new battery and let it charged for two days. But still the same issue.

Initially I changed CPU and later battery. Main power shut off, 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.

 

[Bob O]

WAG Wiring or grounding issue maybe? Can you install a line filter or UPS?

Good Luck

 

[geniusintraining]

Controlling safety

Not sure what kind of safety you are controlling but I would replace it all, I think you need something that you can count on when it comes to safety

 

[joseph_e2]

Is this a modular SLC or a fixed I/O unit? I saw similar behavior with a SLC 5/03. Eventually traced it to the rack power supply. Apparently, if one of the voltages dips below a certain threshold, the CPU automatically resets itself. The explanation I heard is that it can't guarantee control of its outputs if the voltage drops below a certain level, so it kills itself.

 

[Lancie1]

...loose the program and fault led blinks

Because you are getting a fault when PLC power is turned off, my question is what fault code is the PLC showing in the Status file? That might be a hint as to the problem.

Most likely Joseph is correct, and the problem has to do with your power supply, causing some spurious inputs that are being generated the moment you shut off the power. You may need a shut-down routine to stop the robot and to stop generating robot outputs, before killing power to the PLC.

 

[yasirkhi]

Thanks to All

This PLC is monitoring job, safety and operator interface.

This is a modular PLC. Do you guys think, it could be power supply? I will check the grounding, which I didn't check yet. What is in-line filter?

Regards,

 

[Lancie1]

SLC 5/03? Yes, it could be a power-related problem. Another thing to check is whether your PLC internal AC-to-DC power supply is large enough to handle all the I/O that you have connected. An overloaded internal PS can cause some strange effects.

It is easy to overload a model P1 or P2 power supply. You should add up your loads (there is a spreadsheet floating around here that is useful for that) to see if your internal power supply may be overloaded.

 

[OkiePC]

This PLC is monitoring job, safety and operator interface.

Monitoring safety with a SLC is okay. Making control decisions and actions about safety with a SLC is not okay.

Do you guys think, it could be power supply?

Yes. This is actually the most likely cause after the things you have ruled out. I have seen this caused by a power supply at least 4 or 5 times over the past 15 years.

I will check the grounding, which I didn't check yet. What is in-line filter?

Make sure the grounding includes the power supply and the chassis.

In line filters can be helpful in very noisy environments and can be cheap insurance...much cheaper than the cost of downtime in most cases. I see the need for filters more with Micrologix than with larger units with more robust power supplies.

http://www.automationdirect.com/adc/Shopping/Catalog/Power_Products_(Electrical)/Power_Line_Filters

Some folks like to use UPS power too. Here, we have a large central UPS/Filter that supplies control power to most of our larger PLC systems and remote racks.

 

[joseph_e2]

...It is easy to overload a model P1 or P2 power supply. You should add up your loads (there is a spreadsheet floating around here that is useful for that) to see if your internal power supply may be overloaded.

In RSLogix 500, you can go to your IO Config and click on the "Power Supply" button. It will open a dialog that will show your power supply margins and how much power you have left. Note that the rack PS is not part of the IO config. This tool is just for informational uses. If you're anywhere near the limit (or over, of course) you may want to consider upgrading.

 

[Lancie1]

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.

 

[joseph_e2]

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.

It does say that it's an estimate for some generic modules. Is it at least close for standard stuff? I've never really delved deeply into it since I haven't built very many Logix 500 systems from scratch (and most of them have been MicroLogix). I would think (hope, actually) that it would be reasonably correct for stuff that AB makes.