[ANSS-netops] K2 interface with GX-440 modem: k2ew_tcp

[Meremonte, Mark]

We have set up:

-- a K2 Altus for serial datastream at 100 sps on 3 channels, using Mode 1,
baud of 38400, default buffer size, and looks like the default packet size
is "dynamic 2048".  (Not sure what dynamic 2048 really means though.)

--  The K2 is serially connected to a GX-440 with a static public-IP.  Its
serial configuration is set for 38400, 8, N, 1 with no flow control, IP
protocol is set to TCP, and port set to 16030.   Thus the modem (similar to
Lantronix devices which others have used) wraps an IP wrapper around the
serial packets and transmits them to destination IP or our Earthworm host
system which is purposely located not behind a firewall at this time to
simplify testing and too connected to a GX-440 modem with a static
public-IP.

--  K2ew_tcp has the source IP set to GX-440 modem's public IP and the port
is set to 16030.


At first the k2ew_tcp module was "dead" but then in a couple of minutes
after K2 started sending data it switched status -- alive.  However, a
sniffwave showed no data.  a packet sniffer showed packets from the source
IP and port arriving at EW host but packets sizes were small < 80 bytes and
there were numerous re-transmissions arriving.   I expected packet sizes on
the order of 1024 - 2048 bytes.   The re-transmissions seem to indicate
that there is no handshaking between source IP and EW host IP.  Eventually
the k2ew_tcp module went "dead" again.

Thus I am wondering if K2 set up using wrong mode where mode 3 uses full
handshaking, possibly protocol should be UDP rather than TCP to allow
packets to stream without handshaking, or simply have k2ew_tcp.d configured
wrong.

Hope I have described the scenario with sufficient detail to understand.
Mark


-- 
*********************************************************
Mark Meremonte         Geophysicist
U.S. Bureau of Reclamation:  Seismotectonics & Geophysics Group
Denver Federal Center            Work: 303-445-3298  Cell: 303-808-3894
POBox 25007, 85-833000      Email: mmeremonte at usbr.gov
Denver, CO  80225                  Web: http://www.usbr.gov
Ship:  U.S. Bureau of Reclamation, DFC, Bldg. 67-10th Floor, Denver, CO
80225
**********************************************************
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