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Damica

MSG .dn bit never resets

7 posts in this topic

When I start the program the first time and run it, the MSG instruction will send out a message, but the .DN bit will never reset and if I try to use a OTU to unlatch it I get an error that the .DN bit is not writable. So my problem is I can't send out another message unless I go off-line and restart again. I have got to be missing something.

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Can you tell the forum what PLC you are using and post its program if you can?

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Instead, set the OTU to the enable bit (.EN) when you are sure that the previous message is either DONE (.DN) or has encountered an ERROR (.ER) If you have multiple messsages let an OR of the .DN and .ER bits from the previous message enable the next one.

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I have got to be missing something. I just have 2 rungs (And one is the END) Micrologix 1100, rslogix500 on the single rung I have a Switch (I:0.0) (The switch works) then I have a MSG (MG9:0) now I have it set up to send out and email (This all works also) the problem is the MG9:0.DN(done bit) will never reset. Once I throw the switch the MG9:0.en goes true, and a second later the mg9:0.dn bit goes true,(Email has been sent) I can flip the switch back to "False" and the mg9:0.en goes false but the mg9:0.dn stays true. The only way I can reset it is to go offline download the program again and put the micrologix 1100 back into RUN mode. It will then work again for 1 time. What have I missed??

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here's my GUESS ... the Done flag actually does go OFF as soon as you flip the switch back ON again ... but ... then it turns back ON again so fast that you never get a chance to see it even flicker ... try this ... set up a test to send another DIFFERENT message string and then see if that one goes through OK ... I'm betting (pocket change only) that everything is working OK but your reliance on the "green-on-the-screen" indications is making you believe that the message only works once ... are you sending the same message string over and over? ... if you are, then that might make it LOOK like the transfer isn't happening - when actually it is ... if this doesn't help - then consider posting your entire RSS program file and we'll take a look at it for you ... Edited by Ron Beaufort

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As Ron said its doing exactly what it is suppose to do. See excerpt from the manual below

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Yes, I did not fully understand how the MSG instruction worked, After going back and reading several more times I began to understand. I'm sorry I wasted you time, but you did reinforce how it worked, I don't think I will forget this one. Thanks Again

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