New computer, ethernet communication problem

I just got a new Dell Latitude at work. Today I was hooking up to some PLC's and touchscreens, and I could not communicate to anything via ethernet. Particularly a Allen Bradley SLC 5/05 and Red Lion G310. Last week I was able to communicate to both of them with the "old laptop", before the hard drive went out. The SLC 5/05 and G310 are connected through ethernet switch, and there is no internet, or nothing else connected with them. The IP address for 5/05 is 192.168.1.170, the address for G310 is 192.168.1.175, the gateway address is 192.168.1.254, the subnet mask for both of them is 255.255.255.0. The I.T. person, (who is only here once a month, unless we have major network problems in the office) set the computer up to connect to our network in the office for internet purposes and gave the laptop an IP address of something like 169.172.233.211 and a subnet mask of 255.255.0.0., before I got the computer. I went into network connections,local area connection properties, internet protocol (tcp/ip)properties, and checked: use the following ip addreess, and put in 192.168.1.130 for ip address, and 255.255.255.0 for subnet mask, I tried 192.168.1.254 for default gateway and I tried to just leave it blank, and I still could not communicate to either one. On RS Linx, I chose ethernet devices, tried 5/05 ip address on station 0,1,and 2 in cofiguration. RS Who shows unrecognized device with address. On the Red Lion, on link options, I chose tcp/ip and put in 192.168.1.130. The local area connection icon on the taskbar, says status is connected at 100.0 mbps speed, when I have laptop plugged into ethernet switch with plc and touchscreen. I'm sure I don't have the laptop set up right, but don't know what to do. If anyone knows what I am doing wrong please help. Forgot to mention that the windows firewall is off and I am using straight cable from laptop to switch.

Sounds like you did what you should have done, re-assigned the laptop an address on the same subnet as the PLC/HMI. May seen like a silly question but after you made the changes did you reboot the laptop? I know sometimes Linx needs a good restart to pickup nodes.

The first thing you have todo is to check that the internet config of your computer is ok, go to command prompt and there type ipconfig, the computer should return your ipconfig.
then check connection between your pc and the switch on the same command prompt type "ping 192.168.1.170 (slsc 5/05) and you should have a response from the plc.
see attached fig.

In this example what is configured is the wireless connection but in your case it must be the local adapter, this is just an explanation.

hope this will help

Thanks for the reply. I did reboot the laptop after the change. I also just edited my first post and put down that I did turn off windows firewall and I am using straight ethernet cable (tried 2 cables) from laptop to switch. I think its something with the computer's settings because I can't communicate to Red Lion either.

Thanks for the response Widelto, I will do that first thing in morning. What response should I get from slc when I do this?

Are you using Symantec Internet Security? Turn it (Symantec) off and try it again.

I'm not sure about the Symantec security, but I will check. Thanks for the tip.

joe75140 said:

Thanks for the response Widelto, I will do that first thing in morning. What response should I get from slc when I do this?

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You should see the same results but with your ip numbers, if you see something different like "request timed out" that means that your plc is not communicating with those device for some reason, then start checking for antivirus, special comm software, firewalls etc.

Widelto is leading you down the right path.

ipconfig will verify that your ethernet card is operating as expected and is connected. It should also let you know if there is a problem, like the media being disconnected, or a conflict (trying to use an ip address that is already used).

ping, also known as an echo request, is a simple test to verify that two devices are able to communicate. Basically, your computer will ask the other device to acknowledge it. If your computer gets a reply back then you have confirmation that your computer can see the other device.

since the laptop, 5/05, and G3 are the only three devices on the network, you don't need to define a gateway. the gateway address is only used when trying to contact a device on a different subnet. 192.168.1.1 - 192.168.1.254 are all on the same subnet when you use the subnet mask 255.255.255.0.

If ipconfig and ping both pass, then either you've got something in RSlinx configured wrong, or you've got some type of firewall software on your laptop blocking your outgoing requests

Almost certainly your firewall, it may not be blocking outgoing requests but will most certainly be blocking the replies. You will need to add a new range of trusted IP adresses 192.168.1.1 to 192.168.1.254 to the system. The method for doing this varies from firewall to firewall and that assumes that the IT guy left the system open for you to be able to get access.

Bryan

[font=&quot]Were you able to program the G3 via Ethernet with the old laptop? Or did you just use it to view the web server? You may not have Remote Update enabled on the G3, which would not allow you to program via Ethernet. It is worth a shot to connect to the G3 with USB to extract the program (if that was enabled) to verify whether or not remote update was enabled.

Happy Holidays,
Dan[/font]

Doubtful that it's a firewall issue since all your addresses are plugged into the same switch on the same IP network. In any event, starting at the simplest configuration makes the most sense so disable it anyways. OP most likely won't have a problem doing so since he was able to change his IP address.

OP - Monkey and Widelto are leading you down the right path. Don't worry about applications (Norton, etc) yet.

1. You've had several suggestions to "ping" your devices. That should be your first step. Please post the response.
2. If you get a response, I'd guess that your problem is with the software configuration (RSLinx Driver).

BryanG said:

Almost certainly your firewall, it may not be blocking outgoing requests but will most certainly be blocking the replies. You will need to add a new range of trusted IP adresses 192.168.1.1 to 192.168.1.254 to the system. The method for doing this varies from firewall to firewall and that assumes that the IT guy left the system open for you to be able to get access.

Bryan

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gateway or no gateway?

Original PC's IP was 169.172.233.211, most likely his office LAN's IP.

The control subnet is 192.168.1.xxx

Question:

Is it possible that a gateway address could be needed if the control subnet were isolated from the office subnet with router/gateway/bridge?

In that case, could not the PC be isolated, too, from the control subnet by being on the wrong side of a gateway, even though its subnet IP corresponds to the control subnet?

Is putting the OP's PC on 192.168.1.xxx without a gateway IP setting sufficient to connect (assuming other connection settings are viable) if there is subnet isolation through a router/gateway/bridge?

I'm asking this as theoretical question, not proposing it as a solution. I don't know the answer and would appreciate insight.

Dan

This one is a long shot, but our Dell PC's came setup to disable the network cards (LAN and Wireless) when on battery power. That stumped a couple of guys for a while.

Dan - I like where you're going with this. OP is clearly not concerned with communication to/from any other office computers or Internet access.

You're correct that a default gateway would be used to communicate with another network (namely 169.172.0.0, based on his class B network mask). It would be a router or layer 3 switch. A bridge occurs below IP (at layer 2). Think of a switch as a multiport bridge - like connecting another switch via a crossover cable/uplink port.

Putting the PC on the 192.168.1.0 network (as determined by the 24 bit subnet mask) allows it to talk directly to any computer on that same network (IP address of 192.168.1.1-254 with the same subnet mask). Your computer goes to the "default gateway", a misnomer from older technologies, which should maybe be "default router", to communicate with different networks.

His problem is simpler than you're speculating. All 3 nodes are on the same network, plugged into the same switch - no routing required.

OP might be setting himself up for failure if he needs to connect to the Internet or be accessible on the network. It's typically more straightforward to change PC IP addresses than PLC addresses particularly when you have driver applications (RSLinx) and HMIs involved. Or he might have intentionally separated the networks. It's not a big deal to have a second network card in the PC configured to talk to the other network. Heck, you can even bind to addresses to the same card (although typically I wouldn't recommend it). Or he could have his own personnal router. It could even run NAT (network address translation) like your home router, which bends the rules and is probably responsible for the widespread confusion about how IP addressing works.

I'm happy to clarify if anything didn't make sense.

danw said:

Original PC's IP was 169.172.233.211, most likely his office LAN's IP.

The control subnet is 192.168.1.xxx

Question:

Is it possible that a gateway address could be needed if the control subnet were isolated from the office subnet with router/gateway/bridge?

In that case, could not the PC be isolated, too, from the control subnet by being on the wrong side of a gateway, even though its subnet IP corresponds to the control subnet?

Is putting the OP's PC on 192.168.1.xxx without a gateway IP setting sufficient to connect (assuming other connection settings are viable) if there is subnet isolation through a router/gateway/bridge?

I'm asking this as theoretical question, not proposing it as a solution. I don't know the answer and would appreciate insight.

Dan

Click to expand...