memory loss

[norman oliver]

Hi Guys,
I'm running S7 315 2PN/DP + KTP1000 HMI and controlling an oven. I have temperatures displayed and set-points sent to controllers. When customer switches off the SP values are lost and have to be re-instated. How can I retain these values? I'm using MW's to write to the PLC should these be MB's?
Can anyone help please.
Cheers,
Norm
Control panel Builder
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[nonuke]

Retentive memory in S7-300.

https://www.automation.siemens.com/...S=REDIR&PageIndex=1&PostID=200986&Language=en

 

[peterduif]

in tia portal --> plc, tags check retain at the desired tag

 

[norman oliver]

Many thanks for the link. On accessing the retentive tab of the CPU properties I find that the boxes where I insert the DB20 say, is 'greyed' out. Any ideas how I might insert these parameters?

 

[norman oliver]

Thanks for your response. My TIA Portal does not have a retain tab. It looks as though that option is for 1200 plc's and not S7-315. I have wincc Basic V11 SP1. That apart, I would have thought that the values would be installed in the HMI. I have not come across this problem with AB or Mitsi or Fuji HMI's. Any othe ideas?
Regards

 

[peterduif]

ok, now for the 300 series

in cpu properties/retentive memory you can assign which areas are retentive starting from MB0. default is MB0 to MB16 (315 1.jpg)

When using DB`s the retain value is by default checked (315 2.jpg)

i hope this helps

 

[norman oliver]

Thanks for the two views - that would be the answer if I had used TIA to program my plc. I used step 7 V4.5 to program plc and TIA portal for the HMI. My data blocks are in step 7.
Do you think Is there an answer ?
Regards

 

[peterduif]

the answer for step7 is almost the same. ill make a screenshot of that.

 

[peterduif]

Ok, go to HWconfig and then the retentive memory tab. There you can specify the number of memory Bytes that are retentive. It`s the same as in tia portal.
Default MB0 to MB16. So when your values are stored in MB/MW 20 they are not retentive with the default settings.
You could consider to transfer you values to something below MB16 or adjust the hw config to your preffered needs.
im not familiair with the "areas" part in this tab so cant tell you anything about it

Datablocks are retentive by default, but there is an option to make m non retentive.
right click on a DB --> object properties --> then click the general part 2 tab.
There you find a checkbox non retain

 

[norman oliver]

Thanks for that. That looks promising. I have modified the default settings in the box above. I will try this next week and let you know how I get on.
thanks again
Norm

 

[peterduif]

in tia portal --> plc, tags check retain at the desired tag

For anybody who might read this topic
I made a mistake here, didnt look at it properly (i normally only work with db`s)
The attached picture show how to set the retentive area for Memory Bytes.