Hi everyone.

Im fairly new into modbus communication in siemens PLC´s, but im trying to get it working.
I´ve uploaded my project and the byte description.

I´m using a S7-1212 with a CB 1241-RS485. Im trying to interface a Vacon 20 frequency converter.

The communication between the two units is working, and i can read the FB status word and theFB general status word.
But im not able to send anything to the converter (FB control word and FB general control word). I´ve tried to make the bool to word converter, and the other way around, but i cant get the Vacon device to do anything.

And how about the speed reference, am i missing something for controlling this as well ? Now, ive loaded the value 5000 and trying to send it, but it doesn´t come up on my vacon device as a speed ref in the display.

Im thinking, that i maybe send the data in a wrong format, but as this is new for me, i would like some inputs.

Looking forward to hear from you all

Hi all.

I got it working as it should. The link Kaulquappa gave me, got me thinking.

I then edited the send block to go for the mode 1, and the adress to 42001 and everything was working as it should.

Now i got an additional question :)
If i want to communicate with a Vacon 20 more, whats the easiest way to do that ? I tried to copy the send (andchanged the adress from 2 to 3)and recive block and make a new DB to save the data in, but i cant get this to work.

Anyone got a hint for this, or a example project ?

Anyone has