micrologix 1000 retentive memory faults

fleez28

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• Mar 17, 2006

• #1

i have a L16-BWA controller with 3 24v photo eyes and 2 illuminating selector switches inputs, and 2 solenoids and 2 contactors for outputs. everytime i turn the selector switch on to activate the contactors it goes into major fault and loses it's retentive memory. i can't find a short anywhere and the system is grounded properly. the single output i use is supposed to activate 2 contactors and the bulb for the selector switch. when i remove the wires for the contactors the bulb for the switch works fine and so does everything else. but only when the contactors are connected does this issue occur.

if anyone has any info on this i would be extremely thankful

 

mgvol

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• Mar 17, 2006

• #2

This is caused by surges induced by the contactor coils. You need to place surge suppression across the contactor coils, such as a varistor or R/C network. Check with the manufacturer of the contactors; they may make one that plugs directly onto the contactor(s).

 

fleez28

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• Mar 17, 2006

• #3

i am wondering if i am overloading the output or if wiring contactors in parallel is incorrect

 

fleez28

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• Mar 17, 2006

• #4

they are automation direct contactors

 

fleez28

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• Mar 17, 2006

• #5

so would i need 2 supressors or just one since i'm only using i output?? and also why can i force them on in the program with no problem

 

Mickey

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• Mar 17, 2006

• #6

In addition to what mgvol said, install some interposing relays.
To isolated the PLC from the contactors.

 

Last edited: Mar 17, 2006

mgvol

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• Mar 17, 2006

• #7

You would need two, because you are tuning on two inductive loads, regardless of how many outputs you are using. Details can be found on pages 1-8 & 1-9 here:

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1761-um003_-en-p.pdf

 

fleez28

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• Mar 17, 2006

• #8

so is this fault just preventing damage to the contacts?? and why do i lose my memory everytime and have to redownload the program??

 

mgvol

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• Mar 17, 2006

• #9

The fault is caused by the fact that the surges from the contactor coils is corrupting the controller memory. It has nothing to do with the output specifically.

 

fleez28

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• Mar 17, 2006

• #10

ok i see, what's strange also is one of my selector switch lights will only iluminate when my laptop is connected to the the controller

 

fleez28

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• Mar 17, 2006

• #11

is this a grounding issue and the micrologix cable is acting as a ground to the laptop??

 

TimWilborne

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• Mar 17, 2006

• #12

fleez28 said:

ok i see, what's strange also is one of my selector switch lights will only iluminate when my laptop is connected to the the controller

Click to expand...

Yes, I think you have a ground problem

 

TimWilborne

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• Mar 17, 2006

• #13

And you might want to unplug your laptop till you figure it out so you don't blow it up