Hi everyone,

I'm facing an issue with adressing a structure.

I made a usertype to communicate with cognex camera.

Once done i put that usertype a symbol and an adress %I, to be able to reach the camera. But my problem is that the value uint does not follow the adress as shown in the attached photo.

I expect it to be %IW1101 but it goes at %IW1102. Is there any way to fix this?

I'm on a s7-1516 on TIA V17

Thanks

Hello r,farge;

This screenshot, from the Programming Guideline for S7-1200/S7-1500 manual should give you an indication of why the PLC's operating system) only accepts even addresse boundaries in your example.

https://support.industry.siemens.com/cs/ww/en/view/81318674

":PLC data types always end at WORD limits" means that the datatypes (set as symbolic addresses by the operating system of the PLC will fill up until an even boundaryy is reached.

All of us here who have had experience with the S7-300/400 family of processors have had to learn this: all memory addressing must start of a word boundary, with an even address, except for the rarer case of byte addresses.. The S5 PLCs that came before used byte boundaries in their addressing, replaced by word addressing in the S7.  Since the S7-1500 mostly uses symbolic addressing, the case does not show up very often, but it makes sense the this internal rule continues to be followed.

Hope this helps,

Daniel Chartier

r.farge

Hi everyone,

I'm facing an issue with adressing a structure.

I made a usertype to communicate with cognex camera.

Once done i put that usertype a symbol and an adress %I, to be able to reach the camera. But my problem is that the value uint does not follow the adress as shown in the attached photo.

I expect it to be %IW1101 but it goes at %IW1102. Is there any way to fix this?

I'm on a s7-1516 on TIA V17

Thanks

Hello.

What you want to do is not possible (as already explained).
You will not be able to use a single UDT.

Consider taking the raw input bytes and pushing that through some code that maps it into a DB. Have a look at the SCL instructions PEEK and POKE. These will make it more manageable.

But you may want to have a look at what the device supplier offers.

Thank you all for the informations, i assume i'll give up trying this way and maybe juste try another way.

Thanks again

Hi Everyone 

any have fixed this problem? or have an example they want to show? ¨