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Unknown errors from ModBus Read Holding Registers

I have been using the ModBus routines to read registers in a DIRISA A10 Power Monitor.  I'm using the ModBus routines built into my version of Labview 2017.  I have been getting intermittent "unknown errors" (see screen shot of an example) when the holding registers are read.  These errors occur with the following error codes:










This may not be an exhaustive list because every once in a while a new -389xxx error shows up and kills my program.  I have installed code in the program to ignore these errors.  The code continues to run reading the registers.  Note that registers are read by the program every 250 ms.  The program runs without a problem for hours, but eventually dies on one of these errors.  I have also attached a screen shot of the ModBus vi that generates these errors.  I have a couple of questions:  Is there any known fix to this type of "unknown error"?  And is it possible to get a full list of such unknown errors that can be generated by the ModBus routines in Labview?

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@samcat wrote:

Is there any known fix to this type of "unknown error"? 


Hmm... Well I think "Unknown" pretty much says it all.


How can you fix something without knowing what caused the error?


Instead of trying to ignore only certain errors, I ignore them all for four retries. (5 total tries)


My Modbus "Get Primary" block diagramMy Modbus "Get Primary" block diagram


Unfortunately, most readers of this Forum, including some real Experts, have not mastered the skill of being able to read the code that Posters fail to post. If we cannot see "what you did wrong", we are unable to tell you how to fix it. (Bob Schor 28 August 2018)
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