Ethernet/IP, HSE e Profinet

  • Thread starter Humberto de Carvalho
  • Start date
H

Thread Starter

Humberto de Carvalho

I have been reading a lot of thing about industrial ethernet.

I have doubt: I understood that HSE and Ethernet/IP operate on the link layers and physics that already exist in the ethernet 802.3 and Profinet doesn't only work with TCP and UDP, he has a direct channel with the layer link. So profinet need a specific hardware.

Thus I could have HSE and Ethernet implemented more easily in the conventional ethernet (for instance, a PC) but the profinet would not be too easy...

That is correct? I would like to receive commentaries.

Thank you.
 
M

Martin Gallegos

You must know OSI Model, it´s the best way to understand that problem.

Ethernet use Physical and Data link layer Protocols like Profinet, FF HSE, Enet/IP, Modbus TCP/IP, ...use Ethernet.

IP is network layer and TCP is transport layer, some protocols doesn´t use TCP/IP but use Ethernet.

Ethernet is different to TCP/IP, you can use TCP/IP without Ethernet, using modem or ADSL for instance.
 
J
Yes, FF-HSE is easily implemented in a PC, e.g. if you want to make an OPC server. Note that HSE is targeted for process control. We (SMAR) already
make such an OPC server for HSE.

There are a few flavors of PROFINET to suit different applications. Here is my abbreviated take on it:

PROFINET has three communication "channels":
- NRT = Non-real-time: using true Ethernet, TCP/IP, and Windows DCOM
- RT aka SRT = (Soft) Real-time: using true Ethernet, but bypassing TCP/IP
- IRT = Isochronous real-time = not Ethernet, and bypassing TCP/IP

As you can see, RT and IRT are bypassing layers 3 and 4 like traditional Fieldbuses to get better performance.

PROFINET has two application "models":
- CBA = Component Based Automation: Windows COM objects
- IO = Input/Output: slots and indexes like Profibus and Modbus etc.

The channels and models are combined in four varieties with different application areas:
- PROFINET-CBA-NRT: subsystem/package unit integration
- PROFINET-CBA-RT: PLC-to-PLC
- PROFINET-IO-RT: PLC-to-IO
- PROFINET-IO-IRT: motion control

Clearly IRT requires the special ERTEC chip from Siemens. However, you don't communicate IRT with the PC. IRT is used between the motion devices. The motion controllers based on IRT have some four ports. Two of them are used to link to upstream and downstream IRT devices. The remaining two ports can be used for regular Ethernet communication, e.g. with a PC.

The long and short of it is that IRT is not Ethernet and would not be easy to do in a PC, but on the other hand you probably don't want IRT in the PC anyway.

Picking a protocol is based on the application. For process control I would use HSE. For motion control with many axis I would use PROFINET-IO-IRT. In between the choice would need closer study. We (SMAR) make a control system and several devices based on FF-HSE.

For more on HSE take a look at the yellow book "Fieldbuses for Process Control: Engineering, Operation, and Maintenance" buy online: http://www.isa.org/fieldbuses

Jonas Berge
SMAR
===========
[email protected]
www.smar.com
Learn fieldbus and Ethernet at your own pace: www.isa.org/fieldbuses
Learn OPC and automation software at your own pace: www.isa.org/autosoftware
 
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