s7-300 comms probelm

I have an s7-300 and WinnCC problem. I have some experience with S7 programing and winncc programing but noting in deapth as this so please be patient with me.

First, the plc and hmi pc were connected vie ethernet on their own "private" network. I wanted to put them on our main network to be able to access both from a remote pc. I put the main network into a hub along with the plc and hmi pc to connect them to our main network, changed the ip addresses of plc and hmi pc.

I am able to connect to the plc from remote pc and ping it. But if i try and use the accessible nodes feature in S7 I get nothing, shouldn't I at least get the plc listed that is now on the network?

Also, now the hmi and plc are not communicating. I instslled a new connection in tag managment in WinnCC, used the correct ip address of the plc, and copied some tags from old connection but they do not read the plc. Any ideas?

I have s7 on the hmi plc and I am able to connect to the plc and monitor it, but I can not do it with wincc.

Any ideas of what I am doing wrong or what to check on?

Thanks much...

Accesible nodes doesnt work great when communicating over ethernet. However, it doesnt mean that the "nodes" dont exist, just ignore it.

About the HMI:
-Are you able to acces it over the ethernet (try to ping it)?
-Are the PLC and HMI using the same IP range?
-Make sure the PLC and HMI have a unique addres!
-Make sure the gateway (IE; IP of router) is set correctly if you're using a router (not 100% sure about this, speacially if both PLC and MHI are in the same subnet)

Thanks for the reply.

I can ping both the plc and the hmi pc from my office computer. PLC address is 172.16.41.152 and the hmi pc is address is 172.16.41.153. I can connect and monitor the plc from the hmi pc but he hmi doesn't see the plc.

When I hover over an original tag I get this in the window:

Process Value:0
Quality:8
-No connection to PLC
Last Change 2/4/2010 9:35:32am

When I hover over a new connection tag I created I get this:

Process Value:0
Quality:4c
-Start Value
Last Change 2/4/2010 9:51:49am

Is this a "PC Station", i.e. there is the little PC icon "Station Configurator" in the taskbar ?
If so, did you update this PC Station when you changed the configuration ?
What does the diagnostics say in the Station Configurator ?

I got it working. When I copied and pasted the old tags into the new connection it was changing the tag name be adding a _1 to it because that tag name already existed in the old connection. With the new tag name winncc runtime was looking for the old names under the bad connection. If I changed the name in graphics designer I could it to read. So, I cut and pasted, which did not change the name, into the new connection and it worked. Glad I was able to cut and past because I have over 500 tags in the project.

Anyway, thanks for the help this site is great!!!

mrt19