{Siematic Manager}Trouble changing intergers in DB!

Covertfrenchie · Dec 7, 2013

Hey guys I Have a system that has a CPU315-2 DP and I tracked down an adjustment that could be made to make the machine operate more smoothly. The problem is when I make the change in the DB and save then download to the plc and go back online it doesn’t change, the integer stays the same.

Thanks.

PeterW · Dec 7, 2013

Firstly, with Siemens you don't need to change a DB value off-line and download.

If it's a static value (not changed dynamically by the PLC) then you can change it live on-line and then write it into your off-line DB to keep it up to date. Changing a DB value off-line and then downloading to a running PLC may not be advisable, as the other DB values could have been changed to running values and you have now over-written them.

You can also upload from the PLC after a change, but this you would need to be careful, because sometimes you can lose the formatting, so I would do this initially in a copied project.

If you change the DB value and it changes back, it means the program is changing the value back, so you need to find where the program changes it and why.

Edit: easiest way to change a DB value is to create a VAT and put the DB.DBW address in and change from the VAT table.

boneless · Dec 7, 2013

alternatively you can change your view, and change the initial and actual value. next time someone will download the DB, your value will change of you don't.

PeterW · Dec 7, 2013

boneless said:
alternatively you can change your view, and change the initial and actual value. next time someone will download the DB, your value will change of you don't.

Its rare I would download a DB to a running PLC, only if I know that the DB is static values not changed in the code. Don't forget, when you download a DB, you are affecting every word, not just the one you want to change.

boneless · Dec 7, 2013

I agree with you, but better safe then sorry

.

Covertfrenchie · Dec 8, 2013

Here is the section of code:

AN "Hoist brake O/P"
AN "traction position on bay"
O
A "step 003"
JC M00b
L DBW 30
JU M00e
M00b: L DBW 30
L 6
+I
M00e: T #TEMP13
L "Hoist enc count"
L "hoist target enc count"
-I
L #TEMP13
>I
= "Hoist above window"

In the beginning of this FC It opens the DB that the DBW 30 is and that is what I was trying to change. This window that we are monitoring is extremely small and I want to raise the upper limit. Even more what I don’t understand is the value in DBW 30 is 6 and it looks as if it is loading an integer of 6 and then adding them together and transferring them to #TEMP13 but that value shows 6. Why is it not changing to 12.

I would like to clarify that my experience with Siemens PLC is limited to this program. I am proficient with AB. Also when I am troubleshooting this program I have a STL cheat sheet open.

RMA · Dec 8, 2013

What is the result of the first four lines of code? If the result is FALSE then the program loads DBW30 and jumps directly to M00e: T #TEMP13, without adding the 6 to it, which would explain why the observed result in #TEMP13 is 6 and not 12.

L D[AR2P#0.0] · Dec 8, 2013

Covertfrenchie said:
Even more what I don’t understand is the value in DBW 30 is 6 and it looks as if it is loading an integer of 6 and then adding them together and transferring them to #TEMP13 but that value shows 6. Why is it not changing to 12.

Depending on the state of boolean logic bits, this code will either add 6 to DBW30 or not.

Here's the code being monitored with the addition of 6 not being performed:

L D[AR2P#0.0] · Dec 8, 2013

.. and now with the addition taking place. What do you see when you monitor the code?

L D[AR2P#0.0] · Dec 8, 2013

Here's the ladder version for conditioning Temp13

Covertfrenchie · Dec 8, 2013

I will look closer at what you are asking tomorrow when the machine is in use and see how everything changes as the statement of the first few lines of code change.

I do know that I have tried to change the DBW30 and I have tried to change the integer and neither had alternate outcomes on #TEMP13. When I was trying to change the DBW I may not have done it right, I will open a new VAT and monitor it that way and try to make the change.

L D[AR2P#0.0] · Dec 8, 2013

Have you used the xref to check if DBW30 is being written by the plc, is there a HMI connected that could be writing to DBW30?

Wilso · Dec 8, 2013

Covertfrenchie said:
Also when I am troubleshooting this program I have a STL cheat sheet open.

Can't help you with the problem, but would love to see the "STL cheat sheet".

dchartier · Dec 8, 2013

Hello Wilso;
Here is the file I have found on another site a long time ago, referred to as a STL cheat sheet.
Hope this helps,
Daniel Chartier

Wilso · Dec 8, 2013

Thanks a lot.

{Siematic Manager}Trouble changing intergers in DB!

Covertfrenchie

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