Help transmiting data from M241 to modbus device

[Anonymous user]

Hello guys,

I have created some structures in somachine in order to be transmitted with modbus from a M241 PLC. The problem is that all these data are being transmitted but not correctly. For example I have the following data:

W:int:=50;

VA:int:=1000;

Varpower:int:=2000;

Hz:udint:=50;

TotWhInj:ulint:=100;

TotWhAbs:ulint:=100;

So these data are being transmitted with modbus and I am checking with modbus poll whether the transmission is okay or not. So when I check on modbus poll I found out this:

- When I change the value of Hz (That occupy 2 modbus registers) it doesn't change the registers of Hz but change one register of Hz (The second one) and the first register of the next variable. 

I am not sure why that is happening. But what I know is that If change the types from udint and ulint to uint everything works fine.

If someone could help me I would appreciate a lot. Thanks in advance!

[AlastairF]

You may find that the structure is effectively even word aligned because of the udint.

There could be a dummy word inserted after the Varpower variable so the Hz variable is sitting on an even word boundary.

If this was a Modicon M340 or M580, that is exactly what we would get.

There is some description on Help at this location:

Machine Expert > V1.2 > Controllers > M241 Logic Controllers > M241 Logic Controller - Programming Guide > Memory Mapping