S7300 Addressing (Again)!

Kidblue · Nov 15, 2004

Hi, hope somebody could point me in the right direction. First time using S7300. Have managed to configure hardware, cpu etc, download programme, go online, monitor digital I/O - all ok. When i try to download a network that addresses the AI8 module i get errors. All i'm trying to do is view the contents of CH1 of the module by moving it to MW100. I get the error (i think?) that the address i'm using is 'illegal'. I'm using the address the hardware manager assigns(IW288), but no joy. If i change it to IW28 for example it allows me to download it, but obviously i can't then view it.

I appreciate this is very basic, and i've searched the forum for previous posts, just getting a bit bogged down now..........

Any help would be appreciated.

PLucas · Nov 15, 2004

Hi Rob

Give PIW288 a try, I am sure they are addressed as periferal input and output words.

Paul

CT782 · Nov 15, 2004

Can you archive your project and upload it? What CPU are you using?

Polle · Nov 15, 2004

IW : digital Inputs
PIW : analog Inputs

for example:

L PIW 288
T MW100 //analog input-value into MW 100

L IB 4 // inputs 4.0 -- 4.7
T MB 10 //8 digital inputs in MByte 10

same goes for outputs:
QB : digital outputs
PQW : analog output

Polle

Kidblue · Nov 15, 2004

Thanks Paul and others, that nailed it! Bit confused by the "IW : digital Inputs" thing though, i'm just using I0.0 etc for the digital inputs and it seems to work fine?? (or have i mis-interpreted what was said?)

Thanks anyway.

Polle · Nov 15, 2004

you can addres digital i/o as a bit, like you do with I 0.0 but you can also transfer them as a whole byte or word at once (can be very usefull) for example
QB 4 = [Q 4.0 .. Q 4.7] and also
MB 10 = [M 10.0 .. M 10.7]
MW 10 = [MB 10 .. MB 11]
MD 10 = [MB 10 .. MB 13]

Polle

jacekd · Nov 16, 2004

Polle, you must have misunderstood something.
Kidblue, your problem is accessing area that does not exist on your CPU.
With address I* (*=B, W, D) you reach so called Process Image - that is memory in your CPU where state of real IO is stored. But this area is usually very limited in space (on S7-300s it's usally ca. 256 bytes for inputs and another 256 for outputs). Trying to read IW288 it reaches out of limit.
On the other hand reading PIW288 accesses IO module (i.e. IO card memory) directly.
If you moved your IO card addresses below 256 limit (in HWConfig) then you could read with IW address freely.

Polle · Nov 16, 2004

well, i allways use system selection, wich for analog I/O starts from adress 256.
Don't see any use of analog I/O in the PI anyway.

Polle

Rverhoeven · Nov 16, 2004

Think your wrong Jacekd.

The picture says system select. and the adress shown kan always be accessed by means of Ix(.x) however analog values must always be adressed as PI(W) (by the way the P stands for Proces, logically adressing with PIW should be accessing your proces image and not the other way around)

Correct me if i'm wrong

(S7 won't be wrong: banghead )

dchartier · Nov 16, 2004

Hello Rverhoeven;

Correct me if i'm wrong

The P in PIW/PQW means Periphery; it is not a process image access but a direct access on the IO modules, that is implemented at the moment it is requested (not maintained in the process image for a complete scan, as digital IOs are scanned).

Hope this helps,
Daniel Chartier

RMA · Nov 16, 2004

I think Daniel's right there, certainly in the original German, the "P" stands for "Peripherie", otherwise known as hardware interface, i.e. direct access to the hardware.

jacekd · Nov 17, 2004

Dear Rverhoeven,
Looks like you are wrong. And I can assure you that access to "analog values" via I(W) address is possible and depends only on hardware configuration.
Possibly you mixed up PII (Process Image of Inputs), which is part of CPU internal memory; with PI* (*=B, W, D) which stands for Peripherial Input Byte, or Word, or Doubleword.

SaenenDirk · Nov 19, 2004

imho : IW (or IB or ID etc..) will only work when address < 256.

so in this case : use PIW to read the input.

eg :
L PIW288
t MW100

jacekd · Nov 22, 2004

SaenenDirk said:
imho : IW (or IB or ID etc..) will only work when address < 256.

Not 100% true.
For CPUs 312, 313C, 313C-2, 314, 314C-2, 315-2 - <128
For CPUs 317-2 - <256
For CPUs 412-1, 412-2 - <4k
For CPUs 414-2, 414-3 - <8k
For CPUs 416-2, 416-3, 417-4 - <16k.

SaenenDirk · Nov 22, 2004

from the manuals...

anyhow : Kidblue : you need to use the PIW-statement in stead of the IW-statement.

S7300 Addressing (Again)!

Kidblue

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