MUX TROUBLE

[marley]

Hi all, got a wee prob with a mux unit, advise welcome. I have 14 channels of 232 running great, 4 channel of 485 that I cant seem to get working, changed out everything and still no joy, losing frames and packet like wildfire. Thing it could be a common mode voltage on the 2 wire 485, anyone had this prob before.

[Stephen Black]

what type of ROV system are you working on

[Rons_ROV_Links]

What brand/type of MUX are you using?

Did you try swapping the Tx and Rx on one side?

What about the ground?

What type cable (twisted pair etc) are you using?

Did you setup the addresses of the equipment to be connected correctly?

Some info links:

QUICK REFERENCE FOR RS485, RS422, RS232 AND RS423

RS485 serial information

[marley]

Hi all, using a Focal 903 system, it has a 16 channel 232 board, an Adaptable interface board with 3 485 and one tritech hydrophone card installed. The data transmission on the 485 channels is slow. Rovnav works, as it doesnt require a fast data transfer rate but the T3 is another story. Can get telem on the arm but it erratic movement. Its a thales g3 vehicle.

[pipetracker]

Have you tried operating the T3 directly without going through the mux? Water in the 79-way Glenair perhaps? You could also try reconfiguring the T3 to operate on RS232 if you have any spare channels.

Is the video coming over the same FO link?

[marley]

Tks pipetracker, have already tried all your suggestions. The video is fine, at present got the T3 running on 232 no prob. Still like to have the 485 up and running. Conducted testing through the 485 channels with laptops and 485 converters on the bench and no problems found. Leaning toward the possibility of noise on the data lines from a power supply filter in the can. At wits end with this one.

[Rons_ROV_Links]

Hello Marley,

I am only a little familiar with the Focal 907 mux and this one has some dipswitches on the board for baudrate settings for RS485/RS422 etc.
With the Focal 907 their is an option for auto 9600 baud or auto 115.2k baud.
It can be a wrong baudrate setting on the board or so. With the Focal 907 the RS485 channels have a default setting of 9600 baud.

Did you check if the dipswitches are in the correct position (manual).

[marley]

Tks for the info, however have already went thru all the setting, tried different setting. Even changed out the whole mux. What is strange is this setup worked for 3 yrs, not a hitch, then the arm started with erratic movement and got worse. I know the arm workes on 485 because I have another mux system (mini mux 2) for the rov telem and can run the T3 perfectly through this mux system no problem. Getting to be a headache now. Tks again.

[truered]

T3 erratic movements aren’t a symptom of bad telemtry certainly none that i have seen think your dealing with 2 issues there

have you got the Mux software that should have came with the system to do a diagnostics test? the 906 system came with a package

also you can test the 232 channels using hyperterminal

[WidgetKidd]

Have you looked at the fiber end, it maybe dirt building up in the st connector, use a steriwipe to give it a clean.
Does the 903 have a kraft setting , you could try, it works for noisier data.

[TEAMJBR]

Sounds like you’re on a Magnum/Mill possibly with OPAC?

[Jason Garic]

Shilling arms are very picky about quality of data string. T3’s were the worst. Everything else would run fine, even on the same channel; but the T3 would come up with a fatal telemetry error. Ended up being a the back plane.

When you said you swapped mux’s, is that all new cards, backplane, etc?

Also had problems with the baud rate settings on the 903 485 daughter boards. But you’ve already said you’ve checked the buad rates top and bottom sides.

Loop back 485 via serial converter on bottom side? Hyperterminal? Usually when you’ve got a little garbage on the line, you get a crazy reading on the loop back, i.e. typing J’s will give you extra machine language (hearts, spades, symbols)

Any hoo….good luck.

Magnum/Mill possibly with OPAC

How’s that relevant? Survey bottle with the 297 Impulse connectors?

[TEAMJBR]

Soz didnt read the bit at the end and not sure what a Thales G3 vehicle is, Sealion maybe?
Relevant, some subs have quirks faults odd stuff not connected with the focal unit but look like a unit fault!

[elad1986]

Had the same problem with a T3 erratic movement all of a sudden. Most of all it was just jerky as all hell. Ended up having to reset the parameters in the master controller and do a proper service (bleed, purge, etc.)

Sometimes a fibre can be too clean indicating a fatal telemetry error on your T3… thats when spacers and the right placement comes in very handy. It is quite common with these Focal units to have problems with particular channels too.

Hope all went well

[Savante]

http://www.schilling.com/pdf_files/tech_manuals/9188.pdf

not adding anything, but thought the link to the online manual may end up useful to someone !!

good section on troubleshooting eractic single and multiple joint behaviour on page 95 and 96. Lots of potential reasons !!

[Author]

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