sbRIO communication failure

[FabioD]

Hi,

I have a sbRIO 9607. I connect it to my PC with an ethernet cable directly without passing a switch / router. In my place it works fine. However, I met communication failure in the UK. The same connection method, the same configuration in NI Max and the IPV4 in the PC. In the PC, I was able to see the sbRIO 9607 running in NI Max, but when I try to run my labview, it failed to load my .bit file and run the program correctly. 

Has it ever happened to you? Do you have any clues? Could it be a power supply issue? Thank you all in advance. 

Best regards,

Fabio, Giulia

[Bob_Schor · Accepted solution]

I recently tried (and I think I may have succeeded -- I don't recall, because I've been doing much more with a myRIO than with an sbRIO, I think a 9627) to make this connection.  The "tricky" part is getting TCP/IP set up properly, which isn't always so trivial.  The easiest way to do this is from a Desktop machine with a second Ethernet port, as you can more easily access DHCP.  The instructions in the manual do work, but ...

One of the trickier parts is getting the Ethernet cable to work.  Strictly speaking, if you are going from an Ethernet port on a computer to an Ethernet port on another machine (like a sbRIO), you need to "cross-over" certain of the lines, so the Send Line in one device goes to the Receive line in the other.  Crossover cables are rare, getting ever more rare, and often seem to be flakey.  The solution is an inexpensive Ethernet Switch, which should cost < $20, and is usually used where you have one Ethernet "drop" and need to connect PC, Printer, and Scanner to the network.  The "magic" is that the electronics in the Switch "figure out" the crossover connections for you -- just plug the sbRIO and your computer's Ethernet cable into two of the 4 ports, and (as they say where you are) "Bob's Your Uncle".

Bob Schor

[FabioD]

Thanks, Bob! The Ethernet cable might indeed be the cause. Although it had consistently functioned well in our laboratory, we attempted to connect using both direct and crossover cables for further clarification. To our astonishment, both cables worked!

We will try the crossover in the UK and see if this will solve the problem there. Thank you very much again!

Best regards,

Fabio.

[Bob_Schor]

Almost all quality cables are "straight-through", not Cross-over.  About a decade ago (+ or - 5 years), Ethernet chip manufacturers realized (a) 99.9% of cables were Straight-through, (b) cross-over cables were "strange ducks" that were rarely purchased, hence (e) it made manufacturing sense to built "smarts" into the circuitry to detect whether signals needed to be "crossed-over" or not, and (d) do the "cross-over", if necessary, in the chip.  In the rare cases where I knew I was dealing with a "need" for a Cross-over cable (10 years ago), I purchased an inexpensive ($20) 4-port "switch" (the thing you'd plug into your wall's Ethernet jack and then connect 3-4 computer to it), knowing the switch would do any necessary crossover I needed, and I didn't have to inspect the ends of the cable to make sure I had the right type.

A Bad Cable = A Bad Cable.  Cross-over cables are (relatively) rare, "old", not up to CAT-5 or CAT-6 standards.  I'd try a modern (new) CAT-5 cable, which should work, even without the $20 switch.

Bob Schor

[FabioD]

Thank you Bob for the detailed information. We have prepared a switch as a backup plan of the crossover cable. If it is indeed the problem, we will try solutions that are more common and economic like a hub or a modem. 

Fabio