CPU Fault on power loss on a slc 501

[rrparker07]

I'm going nuts trying to figure this one out.

I have a processor that faults every time the power is cycled. The thing is, when it faults it won't let me online to see what the fault is. I get a message that states "can't go online with faulted processor "no program"". It also says must perform download. Under that, there are two buttons: one that says cancel and won that says load from EEPROM. If I click load from EEPROM it loads fine. If I download the program it works. I have tried different combinations of the memory module bits S1/10 - 12 to see if this would help. When I changed them, I also burned the EEPROM so they would match. The battery is brand new.

One side note, when I burn the EEPROM it kicks me offline. I'm fairly new to PLC's and don't know if you're supposed to get a message saying it burned OK.

Any help would be greatly appreciated.

Thanks,
Roy

 

[Adam303]

try searching this site there is a lot of info on this. Basically the program that you have downloaded in to the processor gets erased upon power down. That’s why you get a fault back on power up because there is no program written. Check the battery on the processor or the power supply on the chassis.

 

[rrparker07]

Thanks Adam,

I have looked and I'm comin up short.

 

[Adam303]

http://www.plctalk.net/qanda/showthread.php?t=55369&highlight=slc+fault
http://www.plctalk.net/qanda/showthread.php?t=54252&highlight=slc+fault See Okies response

 

[Adam303]

- Processor Fault​

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"FLT" LED is either RED Solid or RED Flashing​

- Fault persists even after clearing/defaulting the Processor Memory
- Fault occurs either before or after going into RUN Mode​

Check for Error Codes:​

If the processor shows a​

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"FLT" indicator Flashing RED, you should be able to determine the
particular error code by going on-line with your programming terminal loaded with the proper
software RSLogix 500.
See the error code descriptions and causes table found in the SLC 500 Reference Manual and do
recommended action(s) to correct the problem.
To find the processor Major Error code under S:6, click on Processor Status and then the Errors
tab (see below).​

Continue with the following steps if the fault persists;​

Troubleshooting:​

STEP 1)​

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Save any OFFLINE Files in a safe location​

STEP 2)​

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Upload and Backup the existing Application/Project​

STEP 3)​

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Default the processor by disconnecting the battery and shorting the VBB and the GND
for about 40 seconds.
- Reference Document # 14298 for procedure.​

STEP 4)​

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TEST:
- create and download a BLANK/TEST project add the correct I/O modules to configuration
- place the Processor into RUN Mode
- does it still Fault?
- if Yes, could be problem with; Processor, Chassis, Power Supply, or I/O Module(s)​

- if No, next test​

STEP 5)​

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TEST:
- Power down the Chassis and remove ALL the I/O Modules
- create and download a BLANK/TEST Project WITHOUT any I/O modules
- place the Processor into RUN Mode
- if Yes, could be problem with; Processor, Chassis, or Power Supply​

- if No, next test​

STEP 6)​

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TEST:
- Power Down the Chassis and add just one I/O Module at a time
- create and download a BLANK/TEST Project with ONLY the module being tested
- place the Processor into RUN Mode
- does it Fault with a particular module?
- if Yes, could be problem with; that I/O Module​

STEP 7)​

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TEST:
- If the processor does not fault then add one module to the I/O configuration and then go into the​

processor and set it into run mode, do this until all the modules are part of the system.

 

[Adam303]

IMPORTANT!​

A​

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. Make sure that power is removed before inserting a module in the chassis.​

B​

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. If the system has not faulted then proceed with downloading the original program.​

C​

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. Use a TND Instruction at the beginning of the ladder program and then go into run mode.​

D​

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. Keep moving this down until the processor faults, this could point to a problem in the code.​

Note:​

1​

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. Make sure that the power supply is set for the correct voltage.​

2​

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. Check your installation for proper grounding:​

2.1​

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Power supply and chassis grounding wires should be a minimum of 10 AWG to ground bus.​

2.2​

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From ground bus to earth ground the wire should be a minimum of 8 AWG.​

2.3​

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Length of wires should be as short as possible.​

3​

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. Check for proper bounding of the chassis.​

3.1​

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Make good electrical connection between chassis and enclosure through each mounting bolt
and stud.
Remove paint from tapped holes or wherever contact is made.​

3.2​

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Internal Star Washers must be used.​

4​

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. Check for proper surge suppression on all outputs with inductive loads.​

4.1​

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Anytime that an output module is being used to control an inductive device such as
relays, solenoids, motor starters, motors, etc., surge suppressors must be used
(see installation Manual, Publication 1747-6.2 for selection of surge suppressors).​

5​

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. Poor power source (incoming AC voltage).​

5.1​

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Isolation / constant voltage transformer is recommended.​

5.2​

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A clean AC sine wave with the correct frequency and voltage level must be provided to the
System power supply.​

IMPORTANT!!!!​

In all the steps above follow all the recommendations and guidelines found in these publications:​

A​

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. Publication 1747-um011 SLC 500 Modular Hardware Style User Manual
or 1747-6.21 for SLC 500 Fixed Hardware Style User Manual.​

A.1​

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Selecting your Hardware components.​

A.2​

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System installation recommendations.​

B.​

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1770-4.1 Industrial Automation Wiring & Grounding Guidelines for Noise Immunity.​

C.​

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1747-rm001 SLC 500 Instruction Set Reference Manual.​

C.1​

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Trouble Shooting Faults.​

C.2 Error Codes.

 

[rrparker07]

Thanks again Adam,

I had already thought of those things. As far as the disconnect and the power supply (I know this isn't the preferred method of checking this) but I left the chassis powered up and just pulled the processor. The instant I plugged it back in, the fault led lit up. I also cycled the power after pulling all the I/O cards out to rule them out.

Any other suggestions, let me know.

 

[Gil47]

CPU Fault on power loss on a slc 501 site:www.plctalk.net/qanda

Paste the above term into Google search

 

[rrparker07]

Just so you know, my last post references post #4.
I hadn't thought of everything in post 5 and 6. LOL

 

[rrparker07]

BTW Adam,
The fault LED IS blinking and I still get the no program fault.

 

[Adam303]

Can you post the program you are downloading into the SLC 5/01

 

[Ken Roach]

As far as the disconnect and the power supply (I know this isn't the preferred method of checking this) but I left the chassis powered up and just pulled the processor. The instant I plugged it back in, the fault led lit up. I also cycled the power after pulling all the I/O cards out to rule them out.

If it wasn't damaged before, it is now.

While the ControlLogix family of controllers supports removal and insertion under power, doing so to an SLC controller is very likely to damage the controller.

I would replace the SLC-5/01 with a modern SLC-5/03 (the 1747-L531) controller.

 

[Adam303]

If it wasn't damaged before, it is now.

I was just about to say that

 

[Adam303]

I also cycled the power after pulling all the I/O cards out to rule them out.

This will also fault the processor unless you do not have the I'O that you pulled out configured in your program.

 

[Adam303]

Follow all the steps I have posted in post 5 and 6 in detail don’t just go pulling the processor while you have the power on especially if you know that this isn’t a "preferred method" Also be sure to read thru the Slc Modular Hardware Manual that you can find at the AB.com web site.