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Can I Catch Expansion Errors?


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I have a V430 together with an EX-D16A3-R08.  When the connection is lost (cable removed) the V430 immidiatly shows an Expansion error 400.

Is there a way to catch this error and let the operator know that there is an issue but the program continues.

 

Edwin,

 

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I'm with Flex on this one.  Whoever is removing a crucial cable plugged into an operating PLC needs a big smack.  

What...... do they think the socket on the plc is an ethernet port to get to the internet for free?  Fair Dinkum!   🐒's  

cheers, Aus

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I think - the main problem with expansion appear when  expansion is located on big distance from controller.

Maybe cable can not be removed, but expansion can be not powered.

I build v1040 based machine with EX-A2X +IO mounted in separated box on another side of machine.

Sometimes, someone sw off some protection circuit for maintence and do not sw on after.

Then V1040 started, but without part of IO. Only local E46B present.

Then as Flex recommend

3 hours ago, Flex727 said:

spare output keeping a relay closed

on expansion used to power EM.SW relay with NC contact connected to EM. LAMP and Beep sound.  

This EM. relay can not be RESET if IO is not operate via PLC program.

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13 hours ago, kratmel said:

Sometimes, someone sw off some protection circuit for maintence and do not sw on after.

Then V1040 started, but without part of IO. Only local E46B present.

In this case you could do the opposite of what I suggested earlier. Have a spare INPUT on the expansion module that is jumpered out to be always on. If the PLC is powered up without the expansion module the lack of signal from the input would activate an alarm signal (presumably connected to the Snap-In module).

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Thanks for thinking along! In this case the extended io isn't that important. Is it also not possible to automatic reboot after the connection error?  So the PLC boots again without the expansion...

Quote

Whoever is removing a crucial cable plugged into an operating PLC needs a big smack.

This sounded as a great solution, ;) unfortunately I am not always around...

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3 minutes ago, Edwinn said:

Is it also not possible to automatic reboot after the connection error?  So the PLC boots again without the expansion...

Once again, a relay connected to a spare output on the I/O module could be connected to the PLC power supply to force a power cycle when the output drops. You would need to figure out how to wire the relay so that it would only be a momentary drop because that output would not come back after the reboot until the module is reconnected.

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There is no description in visilogic, but I have used SB90 many times to indicate a loss of communication.

I know it works with a snap in block (goes high if the block is removed)

I think it will also work with external expansion.

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3 minutes ago, sgull said:

(goes high if the block is removed)

But how would you prevent the PLC from going into STOP Mode? If it did go high a few cycles before going into stop, then perhaps you could activate SB 300? That would reset the PLC without the module and it would run. Worth testing.

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I must note that the main purpose of any PLC is to safely, stably and correctly manage the devices that users need to control.

Therefore, the failure of the I / O modules must always be confirmed by the user.

If this happens - service technicians should be notified immediately.

It's not about the connection hanging during data transmission - it's about the safe execution of the task using a PLC.

I allow automatic reboots only in the case of a system that is guaranteed to be safe for humans.  But I always try to avoid it.

 

Therefore - we must carefully read the manuals, mount the PLC according to the rules, write programs that are easy to test and get working systems.

If something in the system can fail - it is definitely not a connection with the IO modules.

And this connection must be constantly checked by the emergency monitoring system or a safe PLC must be used (expensive - but without such PLCs, for example, elevators do not work).

 

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You could always go for a "hardware" solution. 

1).  Get rid of the RJ connector and solder the lead directly to the relevant pins.  A bit more fiddly if it ever needs changing, but then again it will always have great contact.

2).  Smother the RJ with hotmelt glue so that it can't be unplugged.  Hotmelt can be useful at times, as it can be "released" or "reapplied" with a bit of judiciously applied heat.

3).  Make a lockable (steel or ally) box that mounts around the back of the plc.  If it is mounted in a door then this is an easy thing to do, (as against on a din rail), and it also gives you much more RF protection.  You must fit an earth lead to it if you go this way, ensure that all cable entries cannot chafe and that some ventilation is still possible.  Been there, done that...in the name of RF immunity.

4).  Hire a grumpy old man from the local old folks home to sit by the plc during use, armed with a big foam bat......   Hey, that'll be me in a few more years.  🙂

cheers, Aus

 

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