Changing a Parameter value online

Daelim said:

Hello Mark

Thanks for the reply, I was thinking of that as well but for that we need the equipment shutdown as that will be an offline change which will require a download. Please correct me if I am wrong.

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Daelim said:

Hello Mark

Thanks for the reply, I was thinking of that as well but for that we need the equipment shutdown as that will be an offline change which will require a download. Please correct me if I am wrong.

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dmroeder said:

You just double click on your rung where it says "121" to start the edit. Change the source B to 5000. Then above the window, you see your grayed-out buttons, assuming that you made no typo's, click the finalize button. The change isn't sent to the PLC until you've assembled the edit (finalize button)

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dmroeder said:

I'm assuming that you only change Source B of that instruction, you can click yes, it will not stop your program or anything like that.

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curlyandshemp said:

No , you can create new tags online

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MarkNightingale said:

Or better still.

Have a tag there instead of the number, and that can be changed on the fly without having to do an online edit.

Cheers

Mark

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Daelim said:

Dear Dmroeder

Thanks for all the replies , I was able to change the parameter online by the method given by you with no hiccups. I Will try adding a controller tag online and will try assigning it to source B online, hope that works out. Thanks again for the help.

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Corsair said:

Notes for general practices for any PLC -

If a constant is a floating-point (a real) it's best to enter it with a '.0' at the end. That shows the compiler your expectation of what the number is. If the compiler doesn't like you entering it that way you need to resolve the conflict.


If you make the value an entered setpoint you may consider putting boundaries on it where you limit it to being between a minimum and a maximum. This tends to avoid a lot of problems including divide by zero issues. PLC code setpoint bounding is the safest best. HMI setpoint entry bounding is also nice but it should be used to supplement (not replace) PLC code bounding. The recent thread about the water-plant problem in Florida is good on this topic.

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dmroeder said:

When you edit, type your tag name into source B. Highlight it and click CTRL+W to open the new tag window. Pay attention to the default data type and scope the tag will be created in. The default data type is a DINT, I'm assuming that is what you want there since the value you are comparing is an integer.

Once your new tag is created, be sure you populate your new tag with the value of 5000 before you assemble the edit, the default value when you create a new integer will be 0. So if you create the new tag and assemble it, the rung will be comparing the input to your new tag with a value of 0.

The advantage here of comparing against a tag rather than a "hard coded" value is that you can change the value of the tag without editing the program.

The disadvantage of this is that it is now easy for others to change. You may or may not want this. Currently, to change the value, it takes a series of steps, which you have to think about. Being able to change it via a tag means the change takes place immediately, so when some one is changing the value from 5000 back to 6000, you can easily accidentally type 6 or 60 or 60000. Also, if you don't want others to be able to change it, not using a tag (as you have it now), you can place the keyswitch in the RUN position to prevent online edits from being assembled. Using a tag, the keyswitch position won't matter, someone will be able to change it. Just some things to keep in mind...

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