Updating initial values of data block with S7

Hello,

I have a question about S7 and how to get the current values from the plc and store them to the offline version so that when I make changes to the software, I don't have to go back to the HMI and re-enter the values that were last used. Is it so that I always have to go to the data block and then change the initial values to the values that are currently being used in the online plc so that they are updated or I can read them somewhere and then copy them back to the data block during the download. These values are things like setpoints that can change from time to time. I don't want to upload a copy of the plc and then have to search through all the data blocks that don't have any comments and the copy the initial values to the original plc program before downloading it after I have made several changes in the program. Thanks for your help!

Best Regards,
PK

There may be an easier way...

Highlight datablock/s in online project then choose PLC->Upload to PG

Unfortunately it is with Step 7 not possible to replace initial values with online values without losing anything. This is one of the main reasons my company has started the development of S7XP Manager. One of its functions is an export of online data to the Step 7 initial values.
http://www.s7xp.com/videos/03_S7XP_Write_Step7_Inital_Values.exe
(Self extractable rar file)
With best regards,

s7xp.com said:

Unfortunately it is with Step 7 not possible to replace initial values with online values without losing anything. This is one of the main reasons my company has started the development of S7XP Manager. One of its functions is an export of online data to the Step 7 initial values.

Click to expand...

I've mainly used 318/317 plcs and my understanding of the Initial Values column is that the data block editor allows you to update all the actual values to the initial values in the offline version only. The only times I've used this are when I've uploaded the datablocks (as Marshy suggests) and they are full of current process values and I want to clear them to the initial values (for a new project for example). If I want to retain the current process values for a backup, I do nothing because when I download the data block, the actual value from the offline version will be copied to the online version - the initial values column has no effect when downloading, restarting etc, it is just a convenience provided in the editor. Now for someone to start developing their own S7 manager so you can copy the actual to the initial values must mean I'm missing something big here - can someone explain why this feature would be so useful ?

For those who haven't read it, this Thread might be of interest.

We are using data blocks for setpoints. Sometimes hundred or more. Everything is setable with a HMI. After commissioning of an installation I want to now exactly what all values of the setpoints are, also when I'm at the office. Now i need to just open te project and get all the latest setpoints.
In the past with the old type S7-300 we had a lot of problems with data blocks and values when writing the eprom. The data blocks starts up with the initial, mostly wrong, values.
And have you ever tried to exend a data block and what happens with your values after a download of the block?

Regards,

L D[AR2,P#0.0]

Did you tried to extend a data block in size?

Regards,

Extending the DB does not change the existing actual values of the offline DB, so, provided you copy online to offline, extend the DB offline, and then download , I've not encountered any problems - what specific actions do you take when you extend a DB that lead to problems with your values ?

Hello,

Thanks everyone for your input on my question. Thanks to S7xp.com for your help especially because S7XP manager is a freaking excellent tool. You guys should try the demo and once you see how easy it is to use and how much time it can save you during commissioning, you will know easily why it is useful. In my job, I am handling processes as well as programming of the machines. So when I go to a customer and want to see the actual process values that they are using compared to the values that I used during the intitial commissioning, this tool is perfect for that. It will be useful also when the customer sends the plc program for us to look at in case we need to download it to our test station plc's to find the bug. If you download the plc and it sends all the initial values that were used during the commissioning, it will be very hard to find the problem. This S7XP manager tool will allow us to go online with the plc via modem or some other connection, launch S7XP manager and upload current values to initial values and then download the plc to a testing plc for debugging. Finally something I like in Siemens although it took another company to expand on it and develop something useful.

Thanks for everyone's input. Surely I will have more questions as I get deeper into S7.

PK

kemppioy said:

Thanks to S7xp.com for your help especially because S7XP manager is a freaking excellent tool. You guys should try the demo and once you see how easy it is to use and how much time it can save you during commissioning, you will know easily why it is useful. In my job, I am handling processes as well as programming of the machines. So when I go to a customer and want to see the actual process values that they are using compared to the values that I used during the intitial commissioning, this tool is perfect for that. It will be useful also when the customer sends the plc program for us to look at in case we need to download it to our test station plc's to find the bug. If you download the plc and it sends all the initial values that were used during the commissioning, it will be very hard to find the problem. This S7XP manager tool will allow us to go online with the plc via modem or some other connection, launch S7XP manager and upload current values to initial values and then download the plc to a testing plc for debugging. Finally something I like in Siemens although it took another company to expand on it and develop something useful.

PK

Click to expand...

Nice idea how to use S7XP Manager. For this kind of operations it may be usefull that S7XP Manager also supports instance data blocks. The next version, currently under test, will support it.