SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

SiePortalDeutsch

Home
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menu temporary not available
- Menue temporary not available
- {{item.title}}

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

USS AND MODBUS PROTOCOL

Created by: Bisaya at: 10/16/2008 3:04 AM (3 Replies)

Rating (2)

Thanks 2

4 Entries

10/16/2008 3:04 AM	Rate (0)
Bisaya Posts: 17 Rating: (0)	Hi experts, Can anyone give me an idea of what is the difference between the MODBUS and the USS protocol. Regards, Bisaya
Bisaya Posts: 17 Rating: (0)
Suggestion To thank Quote Answer

10/16/2008 3:51 AM	Rate (2)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 12/27/2025 Posts: 12474 Rating: (2722)	Hello Bisaya; Modbus is a serial protocol developped in 1979 by Modicon to allow their processors to connect and interchange data so a process could be synchronized in a plant, for example. It was the earliest serial industrial protocol for PLCs, and it was simple and stable enough that it was easily portable for other families of processors; it became a de-facto (without official sanction) standard. There is a Modbus group that maintains the basic implementation rules (Modbus.org) and it has worked on new variations on Modbus, such as Modbus/TCP. The topology used is that of a linear bus, daisy-chained, over RS-232 or RS-485 physical layer. It is a master/slave structure, where only one master is allowed to initiate all requests. Others (the slaves) can only reply to the master's requests. Different "functions" are used to allow the master to specify the type and length of the data it needs to collect from each slave it is connected to. It still reflects its origins in the addressing format used to exchange data; you still have to map the data you want to read/write through Modbus on Modicon register types, 3000x, 4000x, for example. USS is a serial protocol developped by Siemens to control their family of AC and DCdrives. It defines a structure that allows read//writing process data on the drives (control bits, speed reference, and a number of registers in the drive for monitoring purposes) and,also to read/modify drive parameters over the bus. It is also a master/slave structure, but the master can be a PLC (or possibly a PC) only, while the slaves are drives. Topology uses a daisy-chained RS-485 physical layer. USS is still available on Siemens drives (and of course on S7-200 and some S7-300 CPUs) but its structure has evolved into the first Profibus-DP drive profiles, defined as PPO1 to PPO5; it has been applied to SiemensMicro/Masterdrives but also to others (Danfoss, Eurotherm...). If you look at the S7-200 system manual, you will find 2 chapters on the Modbus and USS libraries that will give a lot more details on the protocols and their implementation for S7-200 PLCs. Hope this hel[s, Daniel Chartier
	Last edited by: dchartier at: 10/16/2008 3:53 AM
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users jebril genious2015

3/29/2016 10:53 AM	Rate (0)
Min_Moderator Posts: 4758 Rating: (122)	New question published by Rus26 is split to a separate thread with the subject Micromaster 420 vfd. Best regards Min_Moderator
Min_Moderator Posts: 4758 Rating: (122)
Suggestion To thank Quote Answer

7/31/2017 1:19 PM	Rate (0)
Jen_Moderator Posts: 8171 Rating: (174)	New question published by stretch.str is split to a separate thread with the subject Need to connect inverter for modbus . Best regards Jen_Moderator
Jen_Moderator Posts: 8171 Rating: (174)
Suggestion To thank Quote Answer

Share this page:

Share this page on...

SiePortal

USS AND MODBUS PROTOCOL

Created by: Bisaya at: 10/16/2008 3:04 AM (3 Replies)

Rating (2) Thanks 2

4 Entries

Bisaya

dchartier

Last edited by: dchartier at: 10/16/2008 3:53 AM

This contribution was helpful to

Min_Moderator

Jen_Moderator

4 Entries

Follow us on

Rating (2)

Thanks 2