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OA47

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Joined: 11/04/2012
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Posted: 01:26pm 15 Jul 2014

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Does anyone have experience with SDI-12 and have any thoughts on communicating from a micromite? Could it be as simple as diode-ing the tx and rx of the rs232 to the SDI-12 data line? Any thoughts appreciated.
GM

donmck

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Joined: 09/06/2011
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Posted: 02:01pm 15 Jul 2014

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Graeme Meager said Does anyone have experience with SDI-12 and have any thoughts on communicating from a micromite? Could it be as simple as diode-ing the tx and rx of the rs232 to the SDI-12 data line? Any thoughts appreciated.
GM

I doubt it very much Graeme.
http://www.vegetronix.com/Products/SDI-12-Engine/

USB or RS-232 converters to the SDI-12 bus protocol (Engine) will cost you around $104 USD

Cheers Don...

https://www.32v8.com/d

OA47

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Posted: 09:39pm 16 Jul 2014

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Quote USB or RS-232 converters to the SDI-12 bus protocol (Engine) will cost you around $104 USD

Cheers Don...

Yeah I have noticed the rs232 to SDI-12 converters are fairly expensive and I have been asked to look into getting the micromite + radio terminal units to interrogate and report with the sensor readings. The incorporation of the converter will add to the limited power availability and I was hoping for a short cut.
GM

TassyJim

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Posted: 10:05pm 16 Jul 2014

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I have never had anything to do with the protocol but after a quick look at the specs, it looks like converting the micromite serial to SDI-12 would need an external gate or two and not much else.
You will probably need to use another port to toggle the external gates from TX to RX.

The communications protocol seems to be well documented so should be possible.

I don't have any devices to experiment with so I won't be much help.

Jim

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OA47

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Posted: 12:38pm 18 Jul 2014

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Quote You will probably need to use another port to toggle the external gates from TX to RX.

Good thought Jim, I might try using a 4016 to toggle the Tx and Rx.

GM

TassyJim

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Posted: 01:18pm 19 Jul 2014

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Further thought, the RX could be left as is and simply flush the receive buffer once TX has finished to get rid of the echoed bytes.

The only devices I could find that run the protocol are well above my 'get one to play with' budget.

Jim

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OA47

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Posted: 08:46pm 17 Aug 2014

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Set up a circuit with the MAX232 connected to the COM2 pins and 4066 to acouple of DOUTs but came to grinding halt when I found the necessary configuration to talk to the device is 1200,e,7,1. Am I right to believe it is only the baud rate I can change on the Micromite?

TassyJim

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Posted: 09:38pm 17 Aug 2014

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You might have to calculate the even parity bit yourself and send as 8 bit no parity.

Jim

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OA47

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Posted: 08:42pm 31 Oct 2014

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As the SDI-12 interface is 1200,e,7,1 with combined send /receive line which the micromite can't accommodate and I don't speak fluent c, I was wondering if it would be a big job to write a CFUNCTION to allow com1 to communicate with these devices?

Still in hope
GM

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