REXYGEN Community Forum

ad_t

Member

Registered: 2016-05-09

Posts: 52

SDI support

A client of mine has a particular sensor they would like to use, but it's communication is over SDI-12. I see SPI and generic serial communications are included for, but is SDI; I see SDI is similar to RS-232, so I am hoping it is?

Cheers,

Adam

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: SDI support

Hi Adam,
I have no experience with SDI-12. From what I have learned so far, you will need a SDI-12 converter to connect the sensor to. There are many USB to SDI-12 converters on the market or you can use an Arduino for that. In any case, from the point of view of your algorithm, the SDI-12 converter should act as a standard serial device to which you can send data and read back the responses from sensor(s).

In REX, the REXLANG function block is the way to go for implementation of the SDI-12 protocol (see chapter 4.0). See example 0501-01 on generic serial communication in our repository of examples.

Hope this sheds some light on your problem.

Kind regards,
Jaroslav

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Monarco HAT for Raspberry Pi - Lightweight I/O for monitoring, archiving and control.
Raspberry Pi in industrial automation!

ad_t

Member

Registered: 2016-05-09

Posts: 52

Re: SDI support

Hi Jaroslav,

Thank you for looking into this for me. From the data sheet of one of the sensors we are looking at, I am not sure if the USB interface is even required (data sheet linked below). I may pick up a sensor and give it a go.

https://s.campbellsci.com/documents/eu/ … /cs230.pdf

Thanks for your help again,

Adam

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: SDI support

Hi Adam,
in any case, you need a device to connect the sensors to. You can use either the mentioned USB to SDI-12 converter or you can use one of the Campbell Scientific dataloggers (e.g. CR310 which can provide the measured data via Ethernet). What device are you planning to use?

Jaroslav

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Monarco HAT for Raspberry Pi - Lightweight I/O for monitoring, archiving and control.
Raspberry Pi in industrial automation!

ad_t

Member

Registered: 2016-05-09

Posts: 52

Re: SDI support

Hi Jaroslav,

I was perhaps over simplifying things in my head, but I was thinking of using the sdi-12 products sdi-12 to rs232 converter (https://goo.gl/VT1gqu), linking to either a pi or a PFC100 (750-8102) once it is supported. Do you think that would work?

I wanted to avoid USB, because I planned to use the PFC100, but I will have a look at the Campbell option you suggest.

Thanks again and best regards,

Adam

jaroslav_sobota

Administrator

Registered: 2015-10-27

Posts: 535

Re: SDI support

Hi Adam,
now it makes perfect sense. Yes the Tekbox SDI-12 converter would work. Pigeon PLC might be a nice platform for this application as it has RS232 on board. Any other platform with RS232 port will work as well.

Software-wise, there should be no problem. You'll simply read and write data to/from RS232 serial port in REXLANG.

Jaroslav

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Monarco HAT for Raspberry Pi - Lightweight I/O for monitoring, archiving and control.
Raspberry Pi in industrial automation!

ad_t

Member

Registered: 2016-05-09

Posts: 52

Re: SDI support

Thank you Jaroslav. I'll pick up a Tekbox converter then along with a sensor and give it a go. I'll let you know how it goes.

Cheers,

Adam