Modus Ethernet communication problem

[User002]

Hello!

I have a problem with NI Modbus Library.

When I was testing the modbus Ethernet examples from the NI MB llb I discovered one funny case...

It is working with ordinary Ethernet cable, but does not work properly if I use only 4 wires of the cable (1,2,3 and 6 wires).

I guess it should be enough to use 4 wires.

So, the problem: I use one Slave and several Masters and the ethernet cable category 7. If I use 4 wires of the cable then I can use only one Master.

But when I try to connect another one Master then the Slave buzz and does not answer. I can not understand it...

If somebody knows the problem, answer me, plz

[User002]

I have found the reason... The NI MB library does not work if PC has DNS address, but it connected to the local net without DNS server (i.e. without Internet)...