[etherlab-users] Expected max tx frame rate and a digital off delay issue

[Mike O'Connor]

Hi All

A friend and I have been testing with Etherlab and some Beckhoff Digital
IO and I have a couple of questions.

1. What is the expected max tx frame rate I can expect ?

We adjusted the user land examples to work with our IO and then started
increasing the frequency and found that at 4K we get no issue (maybe a
couple of the dmesg messages below at the start)

[  412.872048] EtherCAT WARNING: Datagram f6bbfc00 (domain0-0) was
SKIPPED 6 times.

but as we increase the rate to 8K then 12K and finally 25K the number of
SKIPPED gets larger and larger

[173178.785515] EtherCAT WARNING: Datagram f6851360 (domain0-0) was
SKIPPED 43476 times.

Now as I understand the product to get an update rate of 10 micro
seconds for a small number of IO (that's what we have) we need to get
the tx frame rate much higher than the standard 250/sec.

We did adjust the intel GigE driver (e100e) to use a
InterruptThrottleRate of 0 which helped a lot with consistency.

I've confirmed via a mirror port on a switch and a capture of the
packets that the IO is replying to every packet we send and that the
rate of sending would seem to match the 8K, 12K, and 25K.

2. Our test program turns on a digital point and then checks a input
which is wired to the output, as a result the input comes on 3ms later
(we are using 3ms filtered inputs) the issue is that some time later the
code turns of the output but the input does not turn off for 8ms. we can
not explain this. Any ideas ?

Thanks
Mike