USS Protocol


Thread Starter

Robert Krueger

I've been a C++ programmer for about 15 years, and built an application for my company to connect to some large machinery. I would like to add the ability to upload and download parameters to Siemens 6RA24 drives, so I would like to build the driver to do this. Is there a tutorial anywhere or clear instructions on how to
communicate to these drives using USS Protocol? I have never built a protocol driver, so I'm hoping that I can find very basic examples or
any other information for USS Protocol. Can you folks help or direct me to the appropriate document?

Robert Krueger

D.C. Pittendrigh

Hi Robert

You are a brave man!!!

There is a document which I have a copy of, you would have to ask your local Siemens rep to look for :


Good Luck
Donald Pittendrigh

McGuire, Paul

I have written USS protocol C++ code using the ObjectSpace Systems Toolkit. Once you create your streaming protocol and adapter (USS support comes with the toolkit, or you can write your own protocols and adapters), just stream your data to the adapter like it was a C++ ostream. Just be sure you stream it back out again in the same order!

They have various bundles of their C++ class libraries, but the USS stuff is in their Streaming Toolkit, which is part of the
Communications bundle. The Systems Toolkit includes all their class libraries, but this may be more expensive than you want to spend. On the other hand, you would get some great threading
classes, and other helpful wrapper classes for things like sockets, files, etc. You should be able to find purchase info on this at .

Paul McGuire
KLA-Tencor Control Solutions
Austin, TX

D.C. Pittendrigh

Hi again Robert

Sorry I pushed send before I finished thinking, there is also a CD available from Siemens called DVA_S7 Object manager, i don't know the part number, but your local Siemens A&D rep should be able to find it for you, this has all the docs on masterdrives, and I think on Simoregs as well. USS should work exactly the same no matter which drive, as it is a procedure you are interested in, the actual drive addresses are found in the drive specific manual. Are U sure USS works with a 6RA24? I am not, I only ever saw them talk
via an add on processor board to a PLC and I am not sure it was USS as this was an S5 135U.


Colin T. Marsh

Siemens can provide communications information describing the USS protocol which is an RS422/485 asynchronous protocol with strict timing requirements and atypical clock speeds of 93.75 and 187.5 Kbaud. Alternatively you could write a modbus serial driver for use with DataLink DL2000-SCIPU communication controller available from Siemens distributors. This device converts serial
modbus protocol to USS and can control parameters etc. for up to 31 networked Siemens vs Drives.

Colin Marsh

Heinz-Juergen Oertel

Are you sure for USS timings ?
I have seen a Application Note for MICROMASTER drives describing usable bit rates as 9600 and 19.2K.

From the Document:
Martin Brown
Siemens Standard Drives
Congleton, Dezember 1997

: 10.4 =DCbersicht Ueber das USS-Protokoll
: Der 6SE21 kann mit bis zu 9600 Baud und der MICROMASTER
mit bis zu :
19,2 kBaud kommunizieren.

I was not able to find the original (product independent) USS description. What source of information do you have?

with best regards / mit freundlichen Grussen

Heinz-Juergen Oertel

Heinz-Juergen Oertel port GmbH phone +49 345 77755-0
Regensburger Str. 7c fax +49 345 77755-20 D-06132 Halle/Saale
mailto:[email protected] Germany

Colin T. Marsh

I'm sure you are correct. In the larger vs drive applications in which the DataLink DL2000-SCIPU interface to Siemens drives is generally used, for performance reasons, communication rates are
more often set to the higher atypical speeds. However USS serial protocol will operate at any speed appropriate to the specific Siemens drive being controlled, including more typical
asynchronous serial speeds of 9,600 and 19,200 baud.
Hello, I have been involved at Siemens development in the 6SE21/31/70 USS implementations, and believe I can be of assistance.

The correct answer regarding baud rates is that yes, the full USS specification allows for baud rates up to 187.5k, but these products in particular only support maximum rates of 9,600 baud (6SE21) and 19,200 baud (6SE31/70) respectively. This is a constraint imposed by the communications devices on board.

This is an important point to bear in mind; an earlier posting by Donald Pittendrigh stated that USS should work the same on all drives. Well, yes, ideally. However, hardware constraints in the low-end drives dictate that only a subset of the full specification can be provided. The development team did a good job; the subset provided gives access to all the major functionality of the drive. The 'Martin Brown' document referred to earlier is the most accurate source of information on USS in these models.

I am no longer employed by Siemens Plc, but work as an independent software consultant in the UK ( Vested Computing Ltd ) and would be happy to offer what assistance I can with USS matters.
Hi I am processing a project just communicate between a uss device(6se3213 micromaster vector) and a PC, I am not quite sure of the connect and please tell me something about "USS". thanks a lot!

Gary Matthews

Hi all. im trying to locate programming examples for the uss protocol. i have been lets say elected to complete a job reqiring realtime +/- control over two nordac vector mc inverters(sk750/1 & sk370/1). I am reqired to control these two units via a rs485 bus in which a windows based pc comunicates thru a rs232/rs485 converter. I am writing the softwares as an activex control using visual basic as it provides an conveniant comm control in wich i can comunicate with the devices. any information at all would be good. preferably vb would be good though i doubt it exists (looked an looked). i can to an extent read c/c++ though do not yet have the skills to complete the project in this language.