RSLinx Classic OEM thinks PLC is still on when it's turned off

@roxusa -

It's like a state change issue. I think I've read just about every forum, post, comment I've found on the internet (three times), but haven't see the same issue I'm experiencing. I'd be curious to see if you see a similar issue.
 
@BruceJW -

I'm using:

RSLinx Classic OEM 3.51.01 CPR 9 SR 5.1

I haven't been able to get to 49 continuous days of capturing since my issue happens every weekend.
 
Since I use VBA in Excel to look at the @IsPresent hot link on my spreadsheet it thinks its still connected

Good; this is exactly what you should be doing.

The activity / status of an OPC or DDE topic should not be affected by the RSWho Autobrowse function. Those topics are defined and already pointed at stations, and Autobrowse is just not necessary to "keep alive" connections.

What type of controllers are you using ? PLC, SLC, MicroLogix, ControlLogix/CompactLogix ?

Which driver are you using ?

A few years ago I ran into trouble with the @IsPresent pre-defined item and the @Mode pre-defined item, because they wouldn't work properly with ControlLogix. I think the workaround was to create a separate Topic just for the @IsPresent, and to manually configure RSLinx Classic to consider the controller to be a PLC-5, even though it was factually a ControlLogix.

This was explained to me as a "legacy code issue. Remember when we had the group up in Vancouver ? The ones that all got fired because of the FactoryTalk launch scandal in 2003 ? Yeah. Good times."
 
@Ken Roach -

You'll have to forgive me if I get this info wrong - I'm an Excel VBA guy not a PLC guy.

PLC mfg.: AB PLC
Device Name: 1756-ENBT/A
 
I decided to scrap the whole RSLinx tag state and just ping the PLC address with VBA. This way, if the PLC is off, I won’t get a good ping and will know the PLC state.

Such an easy fix for days and weeks of fighting data links in Excel.

Thank you all for your time on this. I appreciate your thoughts and suggestions.

John
 
EngMan813 said:
I decided to scrap the whole RSLinx tag state and just ping the PLC address...

Hehe, good old PING!

Some interesting and related reading here, if anyone cares to read it and of course can access it...

26228 - Using RSLinx Alias Topic "Switch On Error" and "Switch On Command"
Access Level: TechConnect

This is a method used specifically for the loss of the RSLinx @ispresent item and how you can use "Switch on Command" with ControlLogix controllers.
Note also how you cannot use "Switch on Error" with Logix controllers.

The use of Alias Topics for failover may suit some users needs in the future.

Regards,
George
 
@Geospark -

Indeed, good old ping! I’m just sorry I wasted so much time with the other methods.

Unfortunately, I don’t have TechConnect access so I can’t read the article.

BUT, I’m pretty sure I read just about ever other article on the internet (twice)!
LOL!!
 

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