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Need assistance : Arduino and Axpert.


viceroy
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Hey all,

Been a while since I've posted anything on here, so I'm a little out of the "scene" so to speak.

I've recently introduced myself to the wonderful world of Arduino, and I'm wondering if anyone has a quick guide for getting an Arduino to communicate with an Axpert?

My axperts are of the old serial variety, so I'm assuming I'll need a RS232 shield.

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Hi viceroy. I assume the power requirements for a serial port on an Arduino, is the same as for a PI. 

Just make sure you make that the serial port has a  MAX3232 chip, as the older MAX232 won’t handle the 3.3v levels of the Pi or Ardduino, whereas the Max3232 will. I got myself a serial port for the PI, just need to install it some or other time. 

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For the USB models, things are problematic. I think the inverter has a usb uart chip in it and expects the other end to act as a usb host, so you'll need a USB shield for the arduino plus implement all the code to talk to whatever is on the other side (probably an ftdi ft232r, but that is a wild guess).

As @Don said, if you need to talk to an actual rs232 port, then you need a max232 (5V) or the other one for 3.3V, depending on what is used by your arduino. The older duemilanove boards are 5V, I believe the minis are 3.3V.

Or you could use one of these that work really well for level shifting.

Simply wire to pins 0/1 and/or PD0/PD1 on the atmega328 while crossing over tx and rx and it should just work.

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 @plonkster I have an UNO which supports both 3.3V and 5V. My axperts are the older serial only models, so I don't really have to mess around with any USB nonsense (for now).

I was planning on getting a RS232 shield so I could incorporate everything into one compact unit, but at half the price, I could get one of these if it will work the same as that sparkfun one.

All I'm looking to do at the moment is have the Arduino link to my BMV700 and monitor SOC, and switch the axperts between PV and Grid.

Nothing serious, just a practical exercise to teach myself something  beyond the usual Arduino LED type projects.

Something else I did was to drive a relay to turn the fridges off when in darkness, and back on when in light, using a delay mechanism so only after 5 minutes (can change this) of either condition will the state change. I figured this to be a good alternative to normal timers which seem to get out of sync over time.

 

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The sparkfun one is actually even simpler than the one you linked. It's literally a few transistors and a charge pump as I recall. The one you linked has a max3232 in it and is a step up. Of course sparkfun stuff gets ridiculously expensive once it hits our shores so the idea would be to get a local equivalent. But at that price, why bother :-)

Sent from my GT-I9195 using Tapatalk


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  • 2 weeks later...
  • 1 year later...

Interesting to see this thread get woken up.

Having got some code working on my PC, that is reading my inverter and my Pylon batteries I pulled an ESP32 out of the drawer thinking about using it for something permanent.

It has multiple serial interfaces so I can use one to talk to my inverter over rs232 - using a Max3232 and then another with a RS485 chip to talk to the batteries that way.

The ESP32 has tons of other features which might be useful; perhaps I can talk to the BMV702 too, and drive some relays for load management.

Anyhow, good to hear that others have done similar

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On 2018/12/23 at 2:16 PM, Elbow said:

Interesting to see this thread get woken up.

Having got some code working on my PC, that is reading my inverter and my Pylon batteries I pulled an ESP32 out of the drawer thinking about using it for something permanent.

It has multiple serial interfaces so I can use one to talk to my inverter over rs232 - using a Max3232 and then another with a RS485 chip to talk to the batteries that way.

The ESP32 has tons of other features which might be useful; perhaps I can talk to the BMV702 too, and drive some relays for load management.

Anyhow, good to hear that others have done similar

Just be careful, the one serial interface talks directly to the memory chip so it can't really be used for anything else.

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On 2018/12/28 at 9:13 AM, SilverNodashi said:

Just be careful, the one serial interface talks directly to the memory chip so it can't really be used for anything else.

Thanks for the hint.

at the moment I’m using an old Pi B+ which is easy to work with.

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  • 2 months later...
On 2017/01/24 at 4:53 PM, plonkster said:

so you'll need a USB shield for the arduino plus implement all the code to talk to whatever is on the other side (probably an ftdi ft232r, but that is a wild guess).

I don't think such a shield exists...

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22 minutes ago, Gnome said:

Well I'll be damned.  USB Host is quite a complicated business, didn't think you could do something like that on such a limited platform

If arduino is too limiting, you can do it quite easily with an STM32 based board.

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