EmonTX V3 stopped transmitting - no periodic LED flash

My EmonTX V3 had been working fine for about two years. I recently had to power cycle it and afterwards it stopped updating on the RPi (uses 433MHz system). I looked for the LED flash (normally every 10 seconds), but could see nothing. Switched 5V power supplies (not running 9V reference). LED comes on initially, then briefly flashes once, then that is it.

Now in an attempt to diagnose what the problem might be I tried to connect up a UART to USB connector (Silicon Labs CP210x), but either there is not output or I didn’t connect it correctly. I used the Arduino Windows software to look at the serial output.

Please confirm what is the correct way to connect the UART to USB connector to the UART on the EmonTX V3.
Tx <-> Rx
Rx <-> Tx
5V nc 5V
3.3V nc 3.3V

Do I need any CT connected to see any output?

Anything else I should test or lookout for?

Unfortunately, there’s a foul-up on the labelling of the pins on the emonTx. It does not follow the usual convention, the crossover from Tx to Rx is done on-board, so the connector pin labelled TXD is looking for the Tx line, likewise the Rx.

That is correct. It has assumed it is running on battery and does not flash the LED as a power-saving measure.

This is what V1.7 of the default sketch prints
emonTx V3.4 Discrete Sampling V1.70 RFM69CW OpenEnergyMonitor.org POST.....wait 10s CT 1 Cal 90.90 CT 2 Cal 90.90 CT 3 Cal 90.90 CT 4 Cal 16.67 RMS Voltage on AC-AC is: ~2V AC-AC NOT detected - Apparent Power measurements enabled Assuming VRMS to be 230V Assuming power from batt / 5V USB - power saving enabled NO CT's detected, sampling from CT1 by default Detected Temp Sensors: 2 RFM69CW Node: 10 Freq: 433Mhz Network: 210 CT1 CT2 CT3 CT4 VRMS/BATT PULSE Temperature 1-2 20134 0 0 0 493 0 215 850 4741 0 0 0 489 0 215 850 1116 0 0 0 485 0 215 850 262 0 0 0 499 0 215 850
as it says, without a c.t.

If you can say which emonTx (V3.2 or V3.4) and which sketch version, that will help.

Ok, it is a V3.4 EmonTx.

How can I know what sketch version it is running?

I don’t think I changed it since I received it.

OK, some real progress now.
I managed to obtain a valid output from the UART (thanks for you help with that).

emonTx V3 DS V1.4 RFM12B
POST…wait 10s
CT 1 Calibration: 90.90
CT 2 Calibration: 90.90
CT 3 Calibration: 90.90
CT 4 Calibration: 16.67
RMS Voltage on AC-AC Adapter input is: ~2V
AC-AC adapter NOT detected - Apparent Power measurements enabled
Assuming VRMS to be 230V
Assuming powering from batteries / 5V USB - power saving mode enabled
NO CT’s detected, sampling from CT1 by default
Unable to detect DS18B20 temperature sensor
RFM12B Initiated:
Node: 10 Freq: 433Mhz Network: 210
0 518
0 489
0 514

Hmm, given this the problem could be with the RFM12B or corresponding receiver on the RPi.

I will look into this further.

Well, it’s not hanging inside the rfm code, which is the usual fault. It could still be the transmitter ‘working’ (accepting input) but not transmitting. Presumably you don’t have a third compatible device to check with?

I have a RF sniffer for 433MHz, so I will be able to tell if it is transmitting.

My main concern was with the main board of the EmonTX failing. If there is a problem with the 433MHz set, then I will probably just move across the data transfer to an ESP8266 NodeMCU unit.

Thanks again for your help.

There is your answer - Discrete Sampling V1.4.

If it is transmitting, then you need to look at the receiver. Is it an emonBase (RPi with RFM12Pi / RFM69Pi module)? - if it is, a favourite fault is the RF board has drooped and touched a higher-numbered GPIO pin. A bit of tape is the cure.

I looked for board drooping, and couldn’t see anything.

I thought I will check the log files on the RPi with the 433MHz module. I thought it would be best to see if data was coming through from the EmonTX and sure enough the whole thing was working properly. Everything EMONCMS local and the public server. hmmm

I took the EmonTX back out to the electrical cabinet and hooked it all up. What do you know, it was all working fine. hmmm

Clearly it just wanted a holiday, or some connection on the EmonTX moved back into place. I will just have to see how it keeps going. Thanks again for all your help Robert.

Sulk Mode. That’s the answer. You accidentally hurt its feelings.