S7 sfc58 "wr_rec"

Hi guys, Happy New Year.

I'm trying to use SFC58 to write data from a DB to the analog output modules, is it possible?

For example if I want to write DB4.DBW0~DBW14 to PQW256~PQW270, how should I write the SFC58?

Is there any other simple way to achive this?

I think your are on the wrong track.

SFC58 and SFC59 are for exchanging data with structured "intelligent" devices, such as HART modules. (disclaimer: That is as far as I understand. I have never had use for SFC58 or SFC59 myself).

If the output modules are on Profibus or Profinet, then you could use SFC15 DPWR_DAT.

However, why send to all analog outputs as one block ?
I am guessing you have a scaling function to scale from engineering units to raw analog output format. And that has to be adapted for every single output channel in the program somehow. Simply put the "T PQWxxx" instructions together with the scaling functions. Makes for readable code too.

I see. Thanks a lot.

How about SFC20? I believe that I can use it to move I/O value to DB. Do you know whether it works for PIW256 or PQW256 and above? When I write parameter P#PIX280.0 BYTE 16, the system didn't allow me. What should I do? Thanks.

S7PP said:

How about SFC20? I believe that I can use it to move I/O value to DB. Do you know whether it works for PIW256 or PQW256 and above? When I write parameter P#PIX280.0 BYTE 16, the system didn't allow me. What should I do? Thanks.

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Hello S7PP;
Jesper's advice earlier was the simplest and the best you could've had.
Meanwhile, here is why SFC 20 cannot work for you: PIW and PQW areas are not supported.
Here is an extract from the System and Standard Functions manual (available in the Simatic/Documentation folder of the computer where you have installed Step 7):

Copying Memory Area with SFC 20 "BLKMOV"
Description
You use SFC 20 "BLKMOV" (block move) to copy the contents of a memory area (= source area) to another memory area (= destination area).
Permissible source areas are the following:
• Parts of data blocks
• Memory bits
• Process-image partition (part process image) for inputs
• Process-image partition (part process image) for outputs

Note: with Siemens docs, understand that if it ain't explicitely permitted, it ain't possible.
Since peripherical addresses (PIW and PQW) are not mentionned, you cannot use them with SFC 20.

Hope this helps,
Daniel Chartier