OTGW problems

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rvoosterhout
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OTGW problems

Post by rvoosterhout »

Hello everybody,

I received my otgw from the nodo shop yesterday and after soldering the final parts on it, I went to install it to my boiler. After connecting everything and setting up mqtt, I started to receive values from my boiler in my homeassistant instance. The only problem is that when i'm using the otgw, I can't connect my Remeha iSense RF to it's base. I can put the base in connecting mode, but the thermostat can't see the base station anymore. When i remove the otgw, I can connect the thermostat to the basestation again.

Another problem I just saw while updating the PIC firmware, is that it shows the boiler connected, when it's not connected. It also says the PIC is not connected, while it is connected.

What is causing this, am I doing something wrong?

Rick
hvxl
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Re: OTGW problems

Post by hvxl »

When just starting with the OTGW, I suggest to only use the OTGW and OTmonitor. Immediately including MQTT and Home Assistant only creates more possible failure sources. Also by using the standard setup, you have a better chance of getting help. I don't use Home Assistant myself. So if that's in the mix, I'm dropping out. Please also specify what type of interface you are using. There are several options that may influence the observed behavior.

Lastly, with fewer components in the setup, there's a better chance of guessing what you mean when you refer to "it". To me it is currently not clear what shows the boiler connected, or what says the PIC is not connected. The OTGW doesn't report those things.

You may also want to follow the troubleshooting instructions. If the problems persist, provide a log showing the issue(s).
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rvoosterhout
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Re: OTGW problems

Post by rvoosterhout »

I'm using a D1 mini with the firmware provided by the url which is in the installation manual from nodo shop.
https://github.com/rvdbreemen/OTGW-firmware/wiki
When I log into that webinterface, it shows that the PIC is not connected, but the boiler is, please see the atachment. I disabled MQTT for now, so homeassistant is not doing anything anymore.
Another strange thing is that when I connect the USB cable to the board, it shows the 24v and the 5v rail active. Shouldn't only the 5v rail be active?
Attachments
otgw.PNG
otgw.PNG (29.07 KiB) Viewed 2627 times
hvxl
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Re: OTGW problems

Post by hvxl »

The board uses a boost converter to generate 24V from the 5V provided through the USB connection. Both voltages are needed, so both LEDs should light up.

I'm going to have to leave the question about what the "Pic connected" and "Boiler connected" indications mean to Robert (or someone else), because I have no idea.
Schelte
rvdbreemen
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Re: OTGW problems

Post by rvdbreemen »

Hi Rick, Schelte,

Based on the information from the webui you provided and the fact that you use my firmware for the Home Assistant integration I can explain some things you. To enable the Home Assistant integration it needs to know if the OTGW is online or offline. To enable that the ESP8266 monitors the OpenTherm messages if it does not see a message from the Boiler or Thermostat for more than 30 seconds. It will report the connection to be offline. For the purpose of the Home Assistant integration if either connection is offline, then it report the PIC / OTGW as offline. This is why there are three values in the webui too.

I fully agree with Schelte that it's best when troubleshooting to step back and make it work with the least amount of options at first. As you seem to use the latest version of the PCB, version 2.3, I would suggest you connect your OTGW using an USB cable to your PC/Mac and then use the OTmonitor application on the serial port. You can even leave out the wemos D1 at this point.

This is the setup with the least components, that way you can make sure that your boiler and thermostat can communicate with the OTGW inbetween. If that does not work correctly, then follow the troubleshoot guide first.

Hope this helps,
Robert
rvoosterhout
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Re: OTGW problems

Post by rvoosterhout »

rvdbreemen wrote:Hi Rick, Schelte,

I fully agree with Schelte that it's best when troubleshooting to step back and make it work with the least amount of options at first. As you seem to use the latest version of the PCB, version 2.3, I would suggest you connect your OTGW using an USB cable to your PC/Mac and then use the OTmonitor application on the serial port. You can even leave out the wemos D1 at this point.

Hope this helps,
Robert
Hi Robert,

I started to do some investigating, and I got it mostly to work. When I remove the D1 mini, connect the otgw to my PC with otmonitor and I connect the Remeha iSense base station, it's working. I get a lot of data from my boiler and I can control the remote override room setpoint using the Thermostat menu (F2). Because I'm using a Remeha iSense RF, it does take 12 minutes for the override setpoint to reach the thermostat, but in the end, it does work.

Now when I connect the D1 mini to the OTGW, I found 2 problems.

- The Remeha thermostat doesn't connect anymore to the base station
I found that the D1 mini uses too much power, for the base station to work. I'm using a 5V 2A USB connector, but this is not sufficient. Luckily, the iSense base station has an additional 5V input, so I connected a 5V 4A power supply to that and now the thermostat can connect to the base station again.

- I can't control the remove override room setpoint anymore.
When I'm using otmonitor on my laptop, with the D1 mini connected to the otgw, setting the remove setpoint (F2) doesn't send this value to the thermostat. In the log, I do see the Command: TT=25, and after that the TT = 25 confirmation message, but after 12 minutes, when the iSense thermostat should change, nothing happens.
I also turned on MQTT again, and tried to set the setpoint using a thermostat card in homeassistant, same story. I do see the Command: TT=25 (or the value I set on the thermostat in homeassistant) in the logging, but after that, no confirmation, which I do get when setting the setpoint using otmonitor.
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Re: OTGW problems

Post by hvxl »

rvoosterhout wrote:- The Remeha thermostat doesn't connect anymore to the base station
I found that the D1 mini uses too much power, for the base station to work. I'm using a 5V 2A USB connector, but this is not sufficient. Luckily, the iSense base station has an additional 5V input, so I connected a 5V 4A power supply to that and now the thermostat can connect to the base station again.
That's not right. The Wemos should use around 250mA. The actual OTGW part (with a thermostat attached) uses less than 100mA. So you can run the whole thing off a standard USB port of your PC, which supplies a maximum of 0.5A. A 2A power supply should definitely be plenty.
rvoosterhout wrote:- I can't control the remove override room setpoint anymore.
When I'm using otmonitor on my laptop, with the D1 mini connected to the otgw, setting the remove setpoint (F2) doesn't send this value to the thermostat. In the log, I do see the Command: TT=25, and after that the TT = 25 confirmation message, but after 12 minutes, when the iSense thermostat should change, nothing happens.
I also turned on MQTT again, and tried to set the setpoint using a thermostat card in homeassistant, same story. I do see the Command: TT=25 (or the value I set on the thermostat in homeassistant) in the logging, but after that, no confirmation, which I do get when setting the setpoint using otmonitor.
Please provide a log showing the issue.
Schelte
wshare
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Re: OTGW problems

Post by wshare »

Several people reported power issues with the Nodoshop board. ( https://discord.com/channels/8129696346 ... 3036333076 ). The board becomes unstable when a thermostat is attached (drawing more power, esp if it has a wireless connection), unless a solid power supply is used. I have a stable OTmonitor with a 2.1 A power supply. Probably it is related to peak voltages.

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Re: OTGW problems

Post by tjfs »

I would also recommend using a high quality short USB cable. It's a good idea to check the voltage between F1 and the USB connector shield, needs to be at least 4.75V.
hvxl
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Re: OTGW problems

Post by hvxl »

The link you mentioned leads me nowhere. But I concur with tjfs, the problems are almost certainly caused by a poor quality USB cable. At least I can reproduce similar behavior when I use a specific USB cable. When I replace that cable by a better quality one, I can run the OTGW (with Wemos D1 mini) perfectly from a USB 2.0 port on my computer. Such ports are limited to 500mA. So, using a 2.1A power supply is totally unnecessary. Also the suggestion that wireless thermostats would be more prone to problems makes no sense. The Opentherm specification defines the voltage and current levels used. A wireless thermostat cannot draw more power than a wired thermostat would. The maximum current supplied to a thermostat is only 23mA. Granted, that's at 18V. But that's still less than 100mA at 5V. With 250mA for the Wemos D1 mini, and a few more mA for the PIC and a few LED's, 0.5A is sufficient.

When selecting a USB cable for the OTGW, make sure it has sufficiently thick wires, especially for the power. Cables are usually marked with a string that looks like 2C/28AWG+2C/24AWG. Here, the 2C means 2 conductors. You may also see 1P, for 1 pair. The 28AWG in the example is for the data wires. The 24AWG is for the power. For a cable of 1.80m, you need at least 24AWG. 22AWG or 20AWG would be better*, and actually essential for longer cables. Old cables may also have deteriorated. In that case, a cable with the suggested AWG value is still no guarantee that it will work.

One way to check your cable is to have all the desired parts connected to the OTGW (thermostat, and optionally the Wemos D1 mini) and then measure the voltage between the pads near the USB jumper marked GND and 5V. If the voltage is lower than about 4.75V, the USB cable has too much resistance. In theory the OTGW would still be able to work even below that voltage. But due to the high resistance of the USB cable, varying current consumption will also result in fluctuation of the voltage, leading to the reported problems. Now, these voltage fluctuations can of course be reduced by adding an electrolytic capacitor (100µF or more) to the OTGW between GND and 5V. And that actually helps. But then the voltage will still be too low. If it gets close to 4.35V, the PIC may experience brown-out resets. Also, all components are calculated for a 5V power supply. Running at a lower voltage may result in other issues. So, the proper solution is to use a good quality, short USB cable.

*: Yes, it's weird. AWG is the acronym for American Wire Gauge. Being an American measurement, it should not come as a surprise that it's weird: Larger numbers mean thinner wires.
Schelte
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