V1040 lost it's memory

[TT_ZX]

I had a customer ring yesterday with an error on the screen:

Stop Mode Fatal Error

003.004.00

No Application

It seems that the PLC lost its memory while it was powered up and running. I haven't been backing the program up to flash for various reasons. Has anyone seen this before. I checked the battery and this was ok, not that it should matter because the PLC was powered up the whole time. I have seen PLC's get corrupt memory before but never lose there memory completely. What happens if the memory in the V1040 gets corrupt?

[linxchas]

2 suggestions:

1. Download program by selecting "Download All & Burn" (make sure after download SI72=1)

2. Check the battery (SB 8 and SB9 must have "0") and check that battery sitting well in the compartment.. I would replace the battery anyway.

[tmoulder]

Sounds like electrical noise. Check your ground, and watch out for feedback paths that can reach the PLC. Remember - isolators are your friends.

[Deke]

I also recently had the same problem, i took out the battery only to find a film of something on the bottom of battery, after cleaning it and putting it back in and then re-downloading the problem has not come back so far.

Deke

[Eric @ SM]

We have had similar issues on a particular group of equipment we built using the V570-57-T20B and V200-18-E1B, a couple "no application" faults and several screen freezes to name a couple.  Because I, nor my co-worker, am not an EE or EET, what sort of test equipment can we use to test for noise or feedback?  Some of the units have had multiple occurances, others none at all (that I am aware).  Or alternatively, how can we better protect the PLC power & grounds as well as the inputs?

[Joe Tauser]

Eric-

 

If you've got a PLC loosing it's mind on an intermittent but regular basis I would strongly suspect electrical transients (spikes).  For starters, if you have any inductive loads connected to the outputs of the -E1B do you have surge suppressors across the coils?  While the relay outputs of the -E1B are isolated, I have seen the PLC go into error when something as seemingly trivial as releasing two small contactors at the same time.    

 

An inductive load always throws energy back into the system when you turn it off as the magnetic field collapses.  It will create a huge (>400V) spike across relay contacts which I guarantee will induce spikes in the other conductors on the board.  You need to give that spike some way to dissipate itself.  If you have AC coils, use RC snubbers.  For DC coils use a 1N4007 diode wired with the band to the positive side.  Put them as close to the inductor as possible.

 

To answer your question on test equipment, if you want to catch noise or spikes you need an oscilloscope, preferably one with digital storage and a one-shot mode.  Then start poking around on all wires connected to the PLC with the trigger set to 50V.

 

Joe T.

[Eric @ SM]

Thank you Joe.  We have some of the outputs controlling resistor suppressed relay coils (generally 12vdc) and others are directly controlling the coils on 9W and 10W valves (also generally 12vdc).  The valve coils have no resistor or diode.  I am assuming that if we can only install the 1N4007 at the E1B, this would be "better than nothing".  Some instances this will be the only location to put the diode.  Other instances we would be able to put the diode within inches of the coil.

 

We do have a small digital storage scope with a 1x/10x probe.  Not sure if it has a "one shot" mode or not.

[Eric @ SM]

We happened to have a small stock pile of 1N-4007 diodes on the shelf, along with 1N-4001 and 1N-5401's.  I'm going to have the controls guys include the 1N-4007's on the next truck to be built, along with an Amperite on-delay relay to keep the PLC from booting when the engine is starting.