Good morning. 

I am re-implementing an application that contains semantics S120 components. The project uses CU320-2PN together with a double control module to control the movement of two synchronous motors. Telegram 111 as communication protocol. I am not very familiar with this protocol and I am trying to understand what is inside the software and understand the functionality. 

The sequence of the motors' movement is configured using the STARTER commissioning tool (see the pic).  I can see that to each positioning there is assigned velocity but then I see in the code that to the Control Unit there is the command to start the sequence, together with parameters "Override" and "MDI_Velocity". What does it stand for? and what is the relation between those variables and the velocity defined in the Traversing block?

Hope my question is understandable.

Thank you!

Hello Joanna,

we can see that your program uses the so called Basic Positioner functionality within the drive. So all the motion control is done within the drive and just the control commands are coming from the PLC program. For the communication to the drive telegram 111 is used - this contains all control words for the basic positioner functionality.

The basic positioner has several different modes to be operated. One mode for example is the MDI mode and another one is the traversing block operation.

MDI mode means that you give a certain position target, the velocity and a start command from your PLC to the drive - the drive will do this job then. Here the effective velocity is the product of the MDI velocity and the override. (real velocity = MDI velocity * override) The override is like a percentage scaling. 

Traversing blocks work a little different - here you define a complete positioning procedure of several movements that are executed automatically after each other (as defined in the table) once you started the task via PLC. Here you can see the configuration table - each step has different parameters such as the position target, velocity, acceleration and so on. 

In both cases the velocity has the unit [1000 LU/min] - LU means length units and is a user defined setting. What this velocity means in physical units (e.g. rpm or m/s) is defined with p2506 (LU per load revolution). This is the factor for the scaling of the position, velocity and acceleration. 

Hope this helps to understand your program a little better.

Thank you for your answer! 

So for example here (see the pic), I have the case when in the code It is traversing block called, but also MDI_Velocity. So which velocity would be executed? 

I will re-implement the program in TIA Portal V16 with Startdrive. should I use exactly the same telegram for communication? I am not sure how should I know which telegram is the best? 

Thank you!

Joanna

Hi,

in this specific code example I assume that the MDI_Velocity has no influence. 

The code selects a traversing block (I think it is number 10 in this case because Bit1 and Bit3 are selected). The velocity should be the one specified in the traversing block table, not the MDI velocity.

When you plan to go on working with the basic positioner, I highly recommend to stay with telegram 111 - this was specially designed for that purpose. Additionally there is a SIMATIC function block available in TIA Portal - search for SINA_POS. This might also help you to do the cyclic data exchange with the drive. 

Another option besides basic positioner is to use the Technology objects of the PLC for motion control - here the PLC does the motion tasks. This is maybe the more simple way when starting from scratch with a new project - but in your case you probably want to keep as much code as possible so I would stay with basic positioner.

Hey!

I was actually planning to use Technology objects. Also when I added to TIA Portal hardware cofing. my equipment. I do not see the option of choosing telegram 111.

How can I know which telegram is the best for me?

Thank you a lot!

Joanna

Hi again,

using Technology objects is really a good idea because the handling and programming is quite simple with the Motion functions such as MC_Power, MC_MoveAbsolute,...

The reason why you can't see telegram 111 is because you first would need to activate the function module EPOS on your drive - then telegram 111 is available and makes sense for that purpose. 

But if you want to go for Technology objects you rather use telegram 105.

So which telegram you use always depends on the application task. Attached you can find a document that I personally created and it describes the most relevant SINAMICS telegrams in my opinion - maybe this brings a little more understanding and helps. The complete list of telegrams and their structure you will find in the official S120 list manual.

Nice! Thank you! 

so one more question, using technology objects I should not use the basic positioner because? 

Joanna

SINAMICS Basic positioner (EPOS) and PLC Technology Object (TO) are the opposite concepts of doing motion control. 

TO is a so called "central" way of doing motion control within the PLC. This costs more PLC utilization but is very convenient for PLC programmers.

EPOS is the "decentral" way of motion control -> the intelligence of calculating the motion profiles is done within the drive directly. Just the control commands come from the overlaid PLC (SINA_POS FB). This costs less utilization on the PLC but you may need some more drive knowledge instead to setup the drive functionality.

Both options have their pros and cons. So it is in my eyes mostly a decision of what you prefer to work with. 

Ok, and just to confirm what I found so far, in the case of using EPOS I can also configure and commission those motors using TIA Portal? I do not need any starter commissioning tool? 

Joanna 

Yes, you can parameterize your hardware, the EPOS functionality and of course also the communication to the PLC via TIA Portal -> the TIA integrated software for SINAMICS drives is called Startdrive (free of charge). So this software addon needs to be installed to find the drives in TIA Portal.

There are a few limitations still for S120 components in Startdrive - for example you cannot parameterize linear motors. But the common S120 devices and motors are included and you can parameterize it.

Hello! 

I have one more question. If I go for the Technology object what will be the role of the Control Unit. 

I have c CU320-2 as a control unit and double motor module.

This is quite a new topic to me and I am a bit confused here

Thank you!

Joanna

Hi,

the CU320-2 is always mandatory to control the S120 with all its components like infeed and motor modules. 

The Control Unit does all calculations - the motor modules are more or less "dumb".

In the case of using Technology objects the CU receives the speed setpoints from the PLC, calculates the speed controller and current controller of all axes and does all monitoring etc. 

So as I said within the drive system it calculates everything. In case you would use EPOS, it would also calculate the position control for the axes.