Requirements

A computer with 1 free full duplex network card
If you are testing a Twister2, then a Twister2 loopback plug and Tetrapolis Power Source or Inferno Power Source.
Linux where C programs can be compiled.
Bertest installed

Network card (NIC) setup

Set up full duplex and 10Mbps with autonegotiation disabled. Full duplex hints. The most used ones:

mii-diag -F 10baseT-FD eth?
mii-tool -F 10baseT-FD eth?
ethtool -s eth? duplex full

Get rid of any traffic into the NIC

Kill all running dhcp daemons running on the interface (possibly ps ax | grep dhcp to list them).
Remove IP address (possibly ifconfig eth? 0.0.0.0)

Postscript / PDF / EPS / BIG png / SVG (Inkscape)

Looping a Twister back

If you have a Twister, put a small piece of wire between the signal terminals of the Twister according to the picture. Set the Twister switches into the "PC" position.

Postscript / PDF / EPS / BIG png / SVG (Inkscape)

Setting up a Twister2

If you have a Twister2, set the switches into the "PC" position. Stick the Twister2 loopback plug into one of the "SIGNAL" connectors.

Running pktloss

If your input and output network card is eth0, run pktloss. If eth1 is input and output, run pktloss eth1. If eth1 is output and eth2 input, run pktloss eth1 eth2.

No DUT connected

In such a case the output will be like this:

1102885167.075454000    100.000 100.000 1024    2224
1102885167.645578000    100.000 100.000 1024    2224
1102885168.215306000    100.000 100.000 1024    2224
1102885168.785415000    100.000 100.000 1024    2224
1102885169.355167000    100.000 100.000 1024    2224
1102885169.925561000    100.000 100.000 1024    2224

Second and third column show packetloss at 10MHz and 5MHz.

Device with packetloss connected

In such a case the output will look like this:

1102885377.652586000    13.868  77.637  1024    2224
1102885378.222727000    14.649  80.372  1024    2224
1102885378.792451000    17.969  83.692  1024    2224
1102885379.362579000    17.188  85.157  1024    2224
1102885379.932404000    22.364  84.961  1024    2224
1102885380.502458000    15.528  79.883  1024    2224
1102885381.072232000    13.379  76.661  1024    2224
1102885381.642390000    15.918  75.196  1024    2224
1102885382.212091000    12.793  87.012  1024    2224

Second and third column show packetloss at 10MHz and 5MHz.

Measurement

Choose output filename describing the measurement you are doing, we'll use example.dat for example. Let it run with output redirected into a file this way for a couple of minutes:

bertest <arguments> > rx_1.dat

Running GNU R

Now run ./analyze example.dat (replace example.dat with your datafile name). example.ps and example.pdf will be generated.

BER in PDF output

Display the resulting Postscript or PDF and go to page 12. There you can see filtered measurement of the BER. Read the higher value of the two. The unfiltered results are on page 2.

Evaluation

BER should be under 10^-9. If it's worse, then something is wrong with the electronics.

Measuring BER of Twister/Twister2 with Bertest