Hi,

I have drive Danfoss VLT 2800 and i need to control it by PLC s7-300 (Simatic manger software )

the communication between the plc and the drive is Profibus and I downloaded the gsd file for vlt2800

I need to know how to start and stop and change speed of the drive vlt 2800 by plc 

Hello,

simple question, did you look at documentation to drive? Generally some steps and examples are described inside documentations, especialy f.ex. with defined I/O buffer elements positions with specific data type, specific byte and bit set options,... If you will add GSD and check internally, you can see possibility to define this I/O buffer for specific purposes and inside at specific position set values as you require.

Hello bishoui;

Ivan is quite correct in suggesting you start by loooking foor documentation on the manufacturer,s site. It is quite easy to find ths manual, quie complete, on Profibus-DP-V1 with a VLT 2800:

https://files.danfoss.com/download/Drives/MG90A502.pdf

The manual stipulates the parameters that mut be set on the drive for Profibus coommunications, follow them carefuly.

On this downloads page, look the the VLT drives Profibus gsd file:

https://www.danfoss.com/en/service-and-support/downloads/dds/fieldbus-configuration-files/#tab-downloads

On this forum, if you use the seach box at the right of this page, you could also find some discussions on Profibus comms beween a S7 CPU and a Danfoss VLT 2800. Here is one of them:

https://support.industry.siemens.com/tf/ww/en/posts/programming-profibus/93156/?page=0&pageSize=10

The most important items for a beginner to focus on for this type of application are (see the screenshot below):

- selecting the appropriate PPO type,, which means choosing the size in bytes and contents of the dedicated telegram between the controller and the drive.

- inside the selected telegram, you need to understand how you build up the HEX value for the control word (start/stop, jog... bits)

- also inside the selected telegram, implementing the speed reference, also in HEX, form HEX 0 (corresponds to 0% of the max speed parameter of the drive) to HEX 4000 (corresponds to 100% ot the max speed parameter of the drive).

Hope this helps,

Daniel Chartier