Hi, I try to connect my raspi with venus 3.52 with a Multiplus 12/500/20 via MK2.2b.
Trying to use the serial port on pins 8 and 10 of the connector prevents the raspi from booting.
Already a cable between the 2 pins causes the problem.
How can I solve it?
My serial port problem is just solved by a change in /u-boot/config.txt.
enable_uart=0
dtoverlay=disable-bt
Now, I have to check, if the Multiplus is found.
Hello. Did you make this work? I’m also trying to use a MK2.2b
Hello Tim,
till now, I did not succeed.
My next step is to make sure the cables are ok and to watch signals on RX and TX.
Hello,
I verified the serial connection, but the venus application does not respond on the serial port.
So, I gave up and bought a MK3-USB, which was correctly found by the application. Now, I have to find ways to control the multiplus via MQTT, but this will be a different topic.
As the Mk2.2b is RS232 and the Rpi expansion pins are 3.3V logic, you have run into a conflict right there.
You will need to use an interface chip to generate the -ve voltage levels needed for the RS232 interface.
The optocouplers are able to run with the Pi voltage of 3.3V. This voltage is supplied on DTR(Pin#4). The signal from Multiplus (or MK2 processor) is fed to the PI successfully. But in the Venus application, the Pi does not answer. I believe, that experienced programmers can manipulate the Pi’s device tree, but this is beyond my knowledge.
My experience is with the Pi3b, where the I/O expansion pins do not have optocouplers, but are direct logic.
Are you able to run a terminal window on the pi and see data being received? You can also check with this to see if typed characters are transmitted on the RS232 line - if no oscilloscope, this can be indicated by a dvm.
you may find this article interesting:
Hello Mike,
with the oscilloscope, I watched received Bytes at the Pi. Also, I could send text to /dev/ttyS0 and saw the result at the RX port of the RS232 of the MK2. Till now, I did not check behind the RX optocoupler in the MK2.
So, physically, the communication should work.
But the Venus application does not try to use the serial TX. The port is not blocked, and I am free to send bytes out via my SSH terminal.
Sorry, I forgot to tell, that I reverted the setting to the original.
Have you tried to communicate with the Mk2 & inverter using the protocol in: “Interfacing-with-VE-Bus-products-MK2-Protocol-3-14”?
If you can get a small script just to interrogate the Mk2, and print the response, this will prove that the communications are good.
Venus should pick up a working interface on a tty, even if it’s not a USB/tty. There is also one file in venus that allows you to enable or disable tty ports, I can’t remember the details at the moment, -if I get time, I’ll see if I can find the details.
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I had to skip the MK2 project unsolved.
It took too much time. With a (freshly bought) USB-MK3, the Venus found the connection on the fly.
I believe, the Victron programmers try to block out the direct serial connection, because for them it is a small thing to support the serial port.