Ethernet comms. via switch

[ragnarg]

Hi all,

I have several similar projects of which I am starting the first one. A single V280 on a small ethernet network with a single switch (or a router) and a single PC. All communications work fine when using a direct link (ethernet crossover cable) between PLC and PC, i.e. using Visilogic, DataXport and UniDDE. When I try to go through the switch or the router there is no way I can even ping the PLC fro the PC. Why on earth is it that I can't even ping the V280 via a dumb switch?

Hope someone can help!!!

Best regards,

ragnarg

[Phil Salkie]

I connect to a V570 via a 24-port switch all the time, for what that's worth. Could there be a cabling issue, or a bad port on the switch? Is it a 10 base T hub and your computer has its port locked to 100? If it's an unmanaged switch, it should just forward any traffic it sees regardless of the IP address ranges involved, so I'd really suspect a hardware/cabling issue.

[ragnarg]

Hi Phil and thanks for your reply.

I have checked (replaced) the cables, and altered the switch ports (or router ports, which I have at the same place) - no change there. I also tried the same setup in another project (V130 <--> Laptop) and it behaves the same i.e. comms work using a crossover cable but not via the switch.

The switch I am using is a D-Link....

http://reviews.cnet.com/switches/d-link-dgs-1005d/1707-6432_7-30540496.html

The Ethernet card in the Vision controllers are set to slave mode. Do I need to send some sort of message from the controller to the network announcing it's existance and it's IP number? I wonder if the switches/routers need some sort of comms. innitiation from the controller???

I am not much of an networking expert but I believe this ought to be pretty much straight forward.... it how confuses my simple mind

Any suggestions....

[Bill Smith]

Suggestions -

1. turn of auto negotiation on the switch and force to 100MB full duplex.

2. make sure you NOT using a crossover cable - it should work either way, but remove it as a potential error source

I would force the Unitronics to the same settings if I could, but I couldn't figure out how to do it.

Conversely, if you find the ports are manually set already, try setting them to auto negotiation.

[ragnarg]

Hi - thanks for your suggestions.

I had a word from site sying that the comms. worked all of a sudden when the normal patch cable was replaced by a screened CAT5 cable. The normal patch cable is in perfect working order. Is it normal that the comms. should halt if a screened cable is not used? Bearing in mind that a direct connection (PLC - PC) via un-screened crossover cable was successful.

Best regards,

Ragnar

[Damian]

Hi - thanks for your suggestions.

I had a word from site sying that the comms. worked all of a sudden when the normal patch cable was replaced by a screened CAT5 cable. The normal patch cable is in perfect working order. Is it normal that the comms. should halt if a screened cable is not used? Bearing in mind that a direct connection (PLC - PC) via un-screened crossover cable was successful.

Best regards,

Ragnar

Sounds like you had a ground loop that the screened cable may be squelching. How close is the switch to both devices?