hi laura, i second john's remarks:
an inexpensive 10Gbit nic card in your computer would make your data streaming task relatively easy, as there are tutorials and several instrument designs that stream data from a roach over 10Gbe into a computer. there's also a lot of good open source software you can use to receive 10gBE data on a computer and send it to a disk drive.... best wishes, dan On Wed, Mar 14, 2012 at 3:18 PM, John Ford <jf...@nrao.edu> wrote: > > Hey Andrew, > > > > Thanks for the reply - we are looking forward to the ROACH 2 in the > > future. > > > > I haven't been able to open all of the tutorials, but I have seen a few. > > So I apologize if I may have missed something obvious, and I would even > > really appreciate an answer that says "hey you, go read about this." I > > see > > that data can be saved using a snap block, and I could save a > concatenated > > set of samples as a single 64 bit integer, and I can save a maximum of > > 2^16 > > of these. Is there a better way of using the roach memory to guarantee > > that I can read and save all of the data continuously? I'm wondering if > > there is perhaps a way of constantly reading from a snap register fast > > enough to insure that we have captured the data continuously and saved it > > to our external computer. > > Hi Laura. In addition to what Dan just said, I want to point out that the > 10m/100m/1g bps port (on at least many ROACH I's) is not reliable at 1 > gbps. > > So you would be streaming 10 MB/s (80 mb/s plus framing) over a 100 mb > link. Pretty risky... > > The 10 gbe solution is better in so many ways. If your computer is within > a few meters of the ROACH, I highly recommend you think about buying a 10 > gb card for the computer. It'll only cost ~$500.00 plus a $100.00 cable, > and will save you a lot of sleepless nights, I think! > > John > > > > > --Laura > > > > > > On Mon, Mar 12, 2012 at 11:59 PM, Andrew Martens <and...@ska.ac.za> > wrote: > > > >> Hi Laura > >> > >> The ROACH does not have a direct 1Ge connection to the FPGA, any data > >> must exit via the PPC if it is not going through the 10Ge links. > >> > >> The ROACH2 however, has a 1Ge link directly to the FPGA. The yellow > >> block has been completed and has been designed to act the same as the > >> 10Ge links (basically the same interface, can be accessed from the PPC > >> if needed, ARP table managed from PPC etc) except that the data rate is > >> lower (8 bit data paths instead of 64 bit). > >> > >> We should be finalising these yellow blocks and making an announcement > >> soon so that people who are interested can start designing for ROACH2. > >> > >> Regards > >> Andrew > >> > >> On Mon, 2012-03-12 at 17:22 -0700, Laura Vertatschitsch wrote: > >> > Hey Casperites, > >> > > >> > I see a lot of data about reliable streaming using the 10GbE ports and > >> > a lovely simulink block to boot. Is there an analogous method for > >> > streaming data out over the 1Gbps ethernet? > >> > > >> > Not sure if someone has written some python control scripts to > >> > accomplish this - I may have just missed it on the wiki. We would > >> > love to stream 10MHz time-domain data off our board. > >> > > >> > --Laura > >> > >> > >> > > > > > >
