GPIB-ENET in a computer with 2 NICs, possible?

[AZVerdugo]

Hi all,

   I'm trying to connect a GPIB-ENET card to a computer. This computer must have 2 Network interface cards. One is for the intranet connection, and the other one is for viewing and controlling the instruments, by using the GPIB-ENET. The GPIB-ENET must only be viewed by that computer, to preserve the privacity of the instrument bank. There is an extrange situation: we can see and control the instruments if we connect the GPIB-ENET to one NIC, and the other NIC is free. But in when we connect the free NIC to the HUB of the intranet, we loss every connection to the GPIB-ENET, and we cannot execute GPIB commands in the instruments. It's like not having it in the MAX.


   Has any of you any idea of what could be happening? The IP configuration of the GPIB-ENET and the two NICs is correct. Each ethernet card has an own IP assigned.

   I know the best option to solve the problem would be the use of an PCI-GPIB, or a USB-GPIB, but we don't have any of them.

   Any help would be welcome



   Regards,

Alfonso

[tbob]

You are right, the best option would be to use a PCI or USB GPIB.  Is it possible that the GPIB commands are going over the GPIB-ENET and one of the NICs at the same time, thereby causing collisions?  I've never used GPIB_ENET.  Why do you need this form of GPIB.  I presently have a system with two NICs, and a GPIB in a PXI chassis.  Works great.  Get rid of the GPIB-ENET and buy a PCI or USB version.  They don't cost that much (about $500 or less).

[AZVerdugo]

Hi tbob,

   I've found an "about 500$" cheaper option. I've been helped by an applications engineer of National Instruments. After three days of interchanging mails,  He suggested me to change the network identifiers, and the GPIB_ENET is now working great. The thing is that you should use different networks identifiers on the two subnets. I didn't realized to do so, because I first worried about giving one IP address to the ENET, and the first IP I asignned to the ENET belonged to the intranet.

   I'm happy of seeing the instrument bank working good. Thank you for your comments

   Greetings from Málaga (Spain)


Alfonso.

[JaimeC]

Hi all,

Well I was the one who suggested that hehe ... teorically when you got 2 NICs the problem is that windows takes one as default and MAX (Measurement and Automation Explorer) only uses the default one to check for instruments/equipment. Normally that is solved changing the order of the NICs on Networks configuration and assigning the default to the one connected to your equipment.

This was a quite extrange issue, because it neither worked making that card to be the default one. I didn't know that windows XP distributes the network traffic to both cards when they are on the same subnet or that it used arbitrary one or another. This behaviour I think happens with Unix but I didn¡t know that for Windows.

Anyway, just take in consideration to have the NIC as default and in another network than the other NIC for any kind of situation using NI equipment and you will be sure that things will work ok,