Siemens S5-115U, CPU941

Weo

Member
W
Join Date
Feb 2006
Location
Sweden
Posts
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Hello,

have a little problem with an old Siemens project.
Have until now only had a RAM-memory, now our customer want a EPROM.

To be able to read/write to the datablocks, you cannot have them in the EPROM, you have to generate these under the start (OB21,OB22), to have them in the internal RAM-memory.

My question:

What does the instruction look like, to generate DB??

I tried with this, see below

IN OB21,22

L KY100,0 // Load 100 byte into ACCU1
G DB 10 // Generate DB10 with length of 100 bytes

Doesn't work, anyone?

Old systems ..
 
Try this:

L KF +49 // Load length into ACCU1
G DB 10 // Generate DB10 with length of 50 words
 
We use the same process on our S5-155U's.

Try this:

L KF +100
G DB 10

I'm not sure if there are restrictions on generating DB's inside OB21,22. We always jump to another block (PB221 in our case) and generate all our data blocks there.

JB
 
Thanks for your answers, but I´ve already tried this. Both in KF format, and also to have the instructions in an FB that I call from my start up OB.

More tip? Are there restrictions on S5 115 that I dont know?
 
If the DB already exists then the G DB command will have no effect, also you must have enough memory available to hold the new block
 
krk said:
If the DB already exists then the G DB command will have no effect, also you must have enough memory available to hold the new block
Click to expand...

Almost 50% free memory area, and the DB doesn´t exist online in PLC ..
 
SimonGoldsworthy said:
How do you know the DB is not being generated ?
Click to expand...

I can´t see the DB online, what do you mean?
When you generate a DB in S5, can´t you see it, but still access it ?? I´m not very good at Siemens S5
 
When you use the G DB method, the block header does not get filled in so I think it will be invisible to your programmer. Try accessing data in the DB in the program, this will tell you if it exists or not (assuming you have no error processing OB's present, the plc should go into stop if the DB doesn't exist)
 
SimonGoldsworthy said:
When you use the G DB method, the block header does not get filled in so I think it will be invisible to your programmer. Try accessing data in the DB in the program, this will tell you if it exists or not (assuming you have no error processing OB's present, the plc should go into stop if the DB doesn't exist)
Click to expand...

Works now, it´s visible in the block header, so you can see the DB as usual.
What I did was the following ..

1.An overall reset from my PG
2.Download all blocks, then my DB was generated and appeared ..

I don´t get it, I should try to blow an EPROM now and check that´s OK too.

Thanks for help
 
The values being changed during the process I don´t want to be overwritten during a "normal" restart. Eg. only when I had a batt fault and the cpu regognizes that, so OB21,OB22 is not good for me .. anyont know what OB to use to start my DB generate?

but I also have to generate them if they aren´t already in the cpu .. hope you understand what i mean

thanks
 
Bump ..

Tried OB19 - Call up when a block is not loaded
and OB32 - Call up when transfer error in DB or in an G DB operation

No generation, CPU in stop mode, run light just flashes green then stop again.

How do you solve this, who works with S5-115 ?
 
Weo

In the 115U CPU941 is OB34, battery failure OB, perhaps you can utilize this OB. I have never used this OB, so I can't offer any guidance on this.

Paul
 

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