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grumpyoldgeek
Newbie

Joined: 30/07/2018
Location: United States
Posts: 36

Posted: 10:14pm 31 Mar 2019

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If you think moisture is still a problem, put one or two bags of desiccant into the enclosure. I've used them in airport weather stations with good results.

erbp
Senior Member

Joined: 03/05/2016
Location: Australia
Posts: 195

Posted: 10:47pm 31 Mar 2019

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Andrew_G said
- what is the realistic maximum USB cable length from a PC running MMEdit to the converter and then to the MM?

Hi,
I'm not sure about the "realistic" maximum cable length, but the USB 2.0 spec specifies 5 meters as the maximum length. USB was never designed for long cable runs.

If you need a longer connection between the MM console and your PC you could consider a pair of HC-12 wireless modules. Connect one to the console Tx/Rx of the MM, and the second via your USB to Serial converter to the PC. This should allow a connection significantly longer than the USB limit.

Cheers,
Phil.

P.S. If you're purchasing HC-12's I suggest you get the genuine ones that Grogster sells.

PeterB
Guru

Joined: 05/02/2015
Location: Australia
Posts: 655

Posted: 01:29am 01 Apr 2019

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G'Day Andrew

I liked RS485 for sending data over reasonable distances.
Is it possible to simplify your system down to the bare minimum that still fails?

Peter

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 02:58am 01 Apr 2019

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I tried running my weather station over a 7 metre USB lead as a temporary measure.
It was not very successful, mainly due to RF getting in from my Amateur repeater that is co-located.

I now do it properly with RS422. RS422 allows for full duplex so updating software works reliably. Power is 12V to the weather box and a 5V switchmode module.
All done over a cat5 cable.

The RS422 runs between the weather station and a Raspberry Pi running ser2net and Cumulus.
This allows me to talk to the weather station from the comfort of my office.
I just have to stop Cumulus then connect through ser2net.
I then restart Cumulus when finished dabbling.

That's how I did my water monitoring which has a 15 metre RS422 run.
Soon to add another 30 metre run to the hothouses.

Jim

VK7JH
MMedit

Andrew_G
Guru

Joined: 18/10/2016
Location: Australia
Posts: 871

Posted: 06:45am 01 Apr 2019

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Thanks again folks - I've been out of www range for a few days.

The remote is still working (with a 1,000uF capacitor across the supply) but I've had it running for more than a week in the past - but I am quietly confident that Jim has fixed it . . .

Jim - how much detail of your RS422 connection can you provide? While I'm keen to track down this problem I also want to start thinking about my next version and RS422, Cat5 cable and 12v supply sounds good (it will be on a 10m high roof surrounded by solar panels with conduit to my study).

Grumyoldgeek, yes desiccant will help but I cannot see any evidence of moisture.
It would also impact the humidity reading but that is of no consequence for fault tracking.

Of course I can't change everything at once or I'll never know what the problem was/is.

Phil and Jim, yes I thought I was nudging it (more than 7m). I can get it down to 4m so if this current trial fails I'll try that.
I'm using Grogster's HC-12s for my data network but of course I can't reprogram the MM via that.

PeterB, you've hit upon my cunning plan - if I can get a console connection long enough, I can leave the remote up a pole so I can reprogram the MM and build up the code until it fails.
If it is up its normal pole I have to climb a ladder, bring it down, take it to my study etc - not desirable at my advanced years (and I'm lazy).

Thanks again folks, Andrew

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 07:07am 01 Apr 2019

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Search Ebay for "RS422 Mutual Transfer TTL Bidirectional Signal Module Full-duplex 422 to SCM"

Apart from soldering a jumper for the terminating resistor, it's plug and play.

Jim

VK7JH
MMedit

Andrew_G
Guru

Joined: 18/10/2016
Location: Australia
Posts: 871

Posted: 09:11pm 01 Apr 2019

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Thanks Jim, I've ordered a brace! Limited data from eBay - is it obvious where the jumper goes? {Edit: looks to me like its a 120 Ohm between the two pads 1/3 of the way from the top in your picture - Thanks, A}

An update:
- the remote (up the pole) misbehaved overnight - it just kept rebooting.
Pressing the reset did nothing (it usually forces a restart).
I turned it off at the power for 30min, turned it on and it is now going again.

Until the RS422 modules arrive I'll try a USB connection to the console (with the above behaviour a software problem is back in the mix).

Thanks,

AndrewEdited by Andrew_G 2019-04-03

TassyJim

Guru

Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 12:16am 02 Apr 2019

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Bridge across the pads circled in red.
That is for the input side.

I didn't bother with the other (outgoing) one.

This is worth a read if you want to do things properly
http://www.ti.com/lit/an/slla272c/slla272c.pdf
The RS-485 Design Guide

Jim

VK7JH
MMedit

Andrew_G
Guru

Joined: 18/10/2016
Location: Australia
Posts: 871

Posted: 12:25am 02 Apr 2019

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Thanks so very much Jim.

Andrew

Andrew_G
Guru

Joined: 18/10/2016
Location: Australia
Posts: 871

Posted: 07:52am 02 May 2019

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An update (of sorts):
The RS422 modules have not yet arrived (a very slow boat from China) but in the interim I've had a couple of goes just putting it all up the pole again. It goes for a week or so, re-boots continuously for a few hours and then settles down and works perfectly (all with no intervention from me).

So I can see what it is doing I've set it up with a tri-colour LED which flashes yellow every 10 seconds when working OK, flashes green when it receives and decodes an incoming message (eg a time/date update every two hours) and red when it is rebooting. I can see the LED at night from my study. I'm also capturing HC-12 messages to an SD card via an OpenLog.

I'll definitely do a new version when I can.

Thanks for all your input,

Andrew

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