protocols and connection technologies

Hey guyzz, can any one just have a word on the protocols, communication technologies, and theIEC or IEEE standards defined for them...

I am a new to the PLC and Communication field...I think its very very important to know about them...

My first doubt is that i learned about IEC 61158 Fieldbus protocol....
In that i saw different types like given below...

[FONT=&quot]AS-Interface, CANOpen, ControlNet, CC-link, DeviceNet, EtherCAT,[/FONT] [FONT=&quot]Ethernet, Powerlink, Ethernet/IP, Interbus, LonWorks,[/FONT] [FONT=&quot]Field bus, Modbus, PROFIBUS, PROFINET IO, PROFINET IRT, [/FONT][FONT=&quot]SERCOS II,I SERCOS interface,[/FONT]

Actually is this all protocols under fieldbus type..

Also another doubt is that, can a RJ 45 connection technology be used for both Modbus and Ethernet/IP protocols,

How a modbus communication is possible with a Siemens S7 400 PLCs...is it Using a CP 443-1

I request you all to pls help me in this matter

Kakka said:

Also another doubt is that, can a RJ 45 connection technology be used for both Modbus and Ethernet/IP protocols,

Click to expand...

I'll only cover this question as I have no experience with the Siemens controls and a general discussion of all available fieldbuses is beyond the scope of a single thread.

Yes, the RJ45 connectors can be used for Ethernet/IP and also for Modbus/TCP. While many connectors are traditionally used or preferred or even specified for certain types of fieldbus connections, the electrons generally don't know or care if they are traveling through an RJ45 or DB9 or whatever.

I would recommend that you start out by learning a bit about the theory behind communications, there's so much to learn that you need a framework. Wikipedia has a good article here...
http://en.wikipedia.org/wiki/OSI_model

Then, you can begin to read up about each individual feildbus, and see how they fit in the seven layer model. For example, Modbus RTU is a simple "Layer 2" fieldbus that can run on either RS-232 or RS-485 at Layer 1. Modbus TCP is an application layer protocol that runs on top of the full Ethernet / TCP/IP Stack. The poorly named Ethernet/IP is also an application layer protocol that runs on top of the full Ethernet / TCP/IP Stack, but you should not confuse the three layers.

Sorry I can't help with your specific question about Siemens. If you don't get any answers, you may want to post again with Siemens S7 Modbus as the title of the thread.