Networked E-120's, occasionally 'reset' themselves

[lotharjt]

Hi, I've got a ship with a pair of Classic E-120s, networked thru a switch (model number not known but it is the std ethernet switched used for installs in 2006 timeframe), a DSM-300 and a Smartpilot.

I've witnessed a number of occasions where the slave plotter will appear to 'lock up' or have frozen data in the databar (depth, lat /long position, SOG/COG) and then a few seconds later the MFD will appear to restart itself, OR, it will declare there is no Master MFD and invite the operator to make it the Master. It seems the likely fault is the HS Seatalk bus has somehow 'failed'. I can simulate the same behavior by disconnect of the bus at the secondary plotter.

Reseating the connector at the plotter may or may not be helping, it seems to come and go with no perceptible pattern.

To a much lesser degree, I've seen the master plotter do the same thing, ie, reset it self with no apparent reason. And occasionally, during these 'frozen data events', the depth data from the DSM will go to 'dashes'.

The varied nature suggests that the HS switch box may be at fault or the ethernet cabling? A visual inspection shows the install was professionally done, cables are secured from vibration / movement and the installed area is dry as a bone.

Any ideas what to do to isolate the problem? Swapping plotters is an idea to see if the tendency for the problem follows the plotter. Changing out one or two HS Seatalk cables is another thought.

Is there update software for the HS Seatalk switch?

Oh, and yes, both plotters are at V5.69 software version. And the first time I witnessed a random reset, the plotters were at 5.52 so upgrading to the latest hasn't resulted in eliminating the problem.

Looking forward to your suggestions.