You know I'm not a student, right?

Hi guys !

I've never used ethernet communications on a PLC for any purpose, ut I see it coming on the horizon, and want to get a jump on it, research-wise.

Therefore, I'm looking for any good (translate : simple) resources on implementing enthernet comms on a PLC, and if you can give a simple explanation, I'd welcome that too.

At this point, I know so little about it, I'm not even sure what questions to ask, and the materials I have found are so far over my head, I can't make sense of them.

For instance : I know what an IP address is, but how is it assigned? Do I program it at set-up? Is it assigned by the master unit? Do ethernet communication system HAVE master units?!

I'm at a loss. As I get more info, I'll try to narrow it down.

Thanks!

TM

I have add Eth-module to RSLogix5000 for fastly programming only and I have had to give IP-address only by DF1-serial port. After re-boot I have changed connection from lap-top-lan-port to Eth-unit.
That's all.
It is possible to use for many other purposes as communication between mill-computers etc.
It is not very inconvenient for Omron, but need much of 'gimmick 3' with Simatic.
Now I have ASi-master with Ethernet (At home) and I can watch from any PC by them IE-Prowsers what inputs are true and false without any application. When I have enough of time, I shall study its program developper, it is as mixed ladder/basic language.

I hope this stimulate you!

Luckily for you, ethernet is the easiest to find information on the 'net because of the widespread use in PC networking. Try a couple searches on the internet for whatever in particular you are looking for.
I have searched and found many very simple and complete descriptions of specific things that I had questions about.

Tim,

First off, don't let it freak you out, it's just like anything else you try to do for the first time. Requires some time and some trial and error. For the most part you really can't damage anything, at least I have never seen anyone let the smoke out by accident.

Second, let me state that I am no expert on this, what I know I learned on my own from trial and error. I probably know just enough to be dangerous. I can do what I need to do without bothering or depending on the IT guys.

The IP address is just that, the address of the unit. Usually you have to assign this, there is something called DHCP which automatically assigns IP Addresses for a set range. For example 192.200.200.220 - 192.200.200.250. For the most part though I would think for PLC use you would want a Static IP Address because you need to know the address of the unit in order to talk to it. If you were to use DHCP it could be anyone of those IP Addresses in the given range at any given time.

I recommend that you get yourself a hub, or a switch, a computer and a PLC with an Ethernet card in it and start trying things out.

Start out setting your computer up with an IP address like 192.200.200.250 and the PLC with 192.200.200.251 and a subnet mask of 255.255.255.0 (I think that is a pretty typical subnet mask, at least where I have worked it is) and see if you can get them to talk to each other.

Good luck.

Ethernet

Tim
Ethernet is the oldest form of computer communications, it isn’t any different than the communications you are accustom to working with, follows most of the same basic rules. You need to get a list of available IP addresses from the system administrator, he should be able to give you a block of addresses if needed. You will assign the IP address in the communication configuration set-up of the PLC, the same manner as setting up your PLC for a DH+ node. If you can set a DH+ node then you will have no problem with Ethernet, with the Ethernet PLC you will be provided with a set-up screen for Ethernet. Take into account that I am only experienced in Allen-Bradley PLC-5 family. Only other concerns are the Ethernet cabling and hardware but it is the same as anything else they must match your application, Ethernet.

Roger

glaverty said:

Tim,
The IP address is just that, the address of the unit. Usually you have to assign this, there is something called DHCP which automatically assigns IP Addresses for a set range. For example 192.200.200.220 - 192.200.200.250. For the most part though I would think for PLC use you would want a Static IP Address because you need to know the address of the unit in order to talk to it.
Good luck.

Click to expand...

See

Internet Protocol Tutorial

Note that 192.200.xxx.xxx is not a valid network domain for local private networks if it is connected to the internet. Small private network domains should start with 192.168.xxx.xxx. Routers know not to forward local addresses in this domain over the internet.

Great link Peter, there is a lot of great information at that site.

As for the 192.200.XXX.XXX, like I said I am no expert, which you just proved. Those are actual IP addresses that are used on our network so they immediately came to mind. I didn't set up the network and I don't know why the IT guy chose those numbers.

Nice Avatar Greg

Notice I borrowed you flashing leds.

As for your 192.200.xxx.xxx domain. As long as your network is not connected to the outside world you are OK.

I always add this cheat sheet about IP addressing to my lecture notes on Ethernet (of course I know the A-B controllers best).

Ten Things You Should Know About TCP/IP

I learned it from watching you!

I "borrowed" the original Avatar from you and modified it, then you "borrowed" it from me, but I modified it again, my light pattern is a little different.

One of these days when I get broadband at home and set up a network this will all come in handy.

Thanks for the feedback, guys! Good information.

Ken : extra thanks for the link to the cheat sheet. That did alot to de-mystify the subject for me. Heck, it even let me make sense of Mr Glaverty's post (Class C!)

TM