internet vs PLC

I have question. can anyone know about controlling PLC via internet?
what I mean is for example, can I just run the plc that is located way far from where I am wia internet?

From my office in the Eastern United States, I've monitored the operation of a PLC in China. Is that far enough away?

The answer is yes.

If your PLC supports any TCP/IP based protocol, then you can create a connection to it via the Internet.

You will have to consider issues of security, VPNs, firewalls etc....but it can be done...and it usually works very well.

sang,

My experiences lead me to think that remote monitoring of a PLC is great, but that remote control can be dangerous. You did say "controlling" a PLC. I recommend actual remote control only where you also have very good remote monitoring of the process, so that you can determine remotely what is happening, or where you have a local operator or technician that can tell you (via phone) what happens when you make a remote change. Otherwise you are flying blind. That said, there are many systems. Rockwell RSVIEW32 has the remote capabililty for an operating system, called the "Active Display System". Also the RSLogix PLC program has an optional dial-in modem that can be connected directly to the SLC 500 PLC's.

I tuned a flying cutoff shear in a steel mill over the internet.

I was in contact with a spotter by phone. Saved lots of $.

hi,
how does one connect a slc-500 to a modem?
using the DH-485-port?

thx

The DH-485 protocol does not pass thru modems. You will need to bridge to a serial protocol convertor of some kind.

It is always best to use the DF1 serial port if you can, but if not Rockwell used to do a 9300-KERAD dail in modem kit for DH-485. I'm not sure if it still available.

Try looking here for these dial in kits: Rockwell DialUps

They aren't cheap, but they are excellent value overall. Getting a computer store modem to talk to any PLC is a hit and miss affair. You might be lucky and get in going in 10 minutes, or it might take you three days..

i just used the Allen Bradley ethernet modem for a customer a few months ago. Took all of 10 mins to get up and running, and this was my first attempt with this product. It cost around 800 bucks, but i found it really easy. It is connected to a 6 SLC 505 processor's via an ethernet switch

You could also try a separate package installed on a PC which has a connection to the PLC (including programming software). Have used both Carbon Copy and PCAnywhere for remote monitoring and simple ( I do mean simple ) changes to Bradley PLCs via a direct line phonecall.

But as some one has already pointed out, its usually best to be at the location, in case something goes wrong when doing a change.

Otherwise for remote monitoring, may be the best way, especially if installed on a SCADA machine to monitor the process anyway.

Regards

Darran