emonTxV3.4 Continuous Sampling will only transmit with USB 5V power connected

Hardware emonTx
,
1

I have two emontx. v3
one of the emontx will only transmit values if the 5V USB power is connected.
only one emontx works 100% with only the 9V AC power connection.
The other one needs the 9V AC voltage reference + 5V USB to work correctly.

Both are powered by identical 9V AC transformers
Only one transmits wirelessly to to the emonPi. The other gets stuck with RED LED constantly on.
The good emontx values arrive in emonPi
The bad emontx values appear to transmit, but the values seen in emonPi CMS are all ZERO.

i worked out that if I add 5V DC (via FTDI or USB cable) then the bad emontx works fine.

Is there a configuration setting (hardware or software) i am missing on the bad emontx to allow it to operate correctly exclusively on the 9V AC power supply? and not need the 5V USB connetion to be applied?

Good emontx config and versions

emonTx V3.4 EmonLibCM ContinemonTx V3.4 EmonLibCM Continuous Monitoring V2.00
OpenEnergyMonitor.org
No EEPROM config
Settings:
Group 210, Node 15, Band 433 MHz

Calibration:
vCal = 298.22
assumedV = 240.00
i1Cal = 90.90
i1Lead = 4.20
i2Cal = 90.90
i2Lead = 4.20
i3Cal = 90.90
i3Lead = 4.20
i4Cal = 16.67
i4Lead = 6.00
datalog = 9.96
pulses = 1
pulse period = 100
temp_enable = 1
Temperature Sensors found = 0 of 1
Temperature measurement is NOT enabled.

RF whitened
RFM69CW only Node: 15 Freq: 433MHz Group: 210

bad emontx and config

emonTx V3.4 EmonLibCM Contide
emonTx V3.4 EmonLibCM Continuous Monitoring V2.00
OpenEnergyMonitor.org
No EEPROM config
Settings:
Group 210, Node 16, Band 433 MHz

Calibration:
vCal = 268.97
assumedV = 240.00
i1Cal = 90.90
i1Lead = 4.20
i2Cal = 90.90
i2Lead = 4.20
i3Cal = 90.90
i3Lead = 4.20
i4Cal = 16.67
i4Lead = 6.00
datalog = 9.96
pulses = 1
pulse period = 100
temp_enable = 1
Temperature Sensors found = 0 of 1
Temperature measurement is NOT enabled.

RF whitened
RFM69CW only Node: 16 Freq: 433MHz Group: 210

They look identical to me

both emontx are running

/*
  emonTxV3.4 Continuous Sampling
  using EmonLibCM https://github.com/openenergymonitor/EmonLibCM
  Authors: Robin Emley, Robert Wall, Trystan Lea
  
  -----------------------------------------
  Part of the openenergymonitor.org project
  Licence: GNU GPL V3
*/
2

emon hub shows this in the log for the bad emontx with only 9V AC connected (From Node : 16)
notice all the reported values are zero

2021-09-13 12:33:09,557 DEBUG    RFM2Pi     7570 Timestamp : 1631532789.551694
2021-09-13 12:33:09,558 DEBUG    RFM2Pi     7570 From Node : 16
2021-09-13 12:33:09,559 DEBUG    RFM2Pi     7570    Values : [0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
2021-09-13 12:33:09,560 DEBUG    RFM2Pi     7570      RSSI : -73
2021-09-13 12:33:09,560 DEBUG    RFM2Pi     7570 Sent to channel(start)' : ToEmonCMS
2021-09-13 12:33:09,561 DEBUG    RFM2Pi     7570 Sent to channel(end)' : ToEmonCMS
2021-09-13 12:33:09,631 DEBUG    MQTT       Publishing: emon/emontx3cm16/MSG 0
2021-09-13 12:33:09,632 DEBUG    MQTT       Publishing: emon/emontx3cm16/Vrms 0
2021-09-13 12:33:09,634 DEBUG    MQTT       Publishing: emon/emontx3cm16/P1 10
2021-09-13 12:33:09,635 DEBUG    MQTT       Publishing: emon/emontx3cm16/P2 0
2021-09-13 12:33:09,636 DEBUG    MQTT       Publishing: emon/emontx3cm16/P3 0
2021-09-13 12:33:09,637 DEBUG    MQTT       Publishing: emon/emontx3cm16/P4 0
2021-09-13 12:33:09,639 DEBUG    MQTT       Publishing: emon/emontx3cm16/E1 0
2021-09-13 12:33:09,640 DEBUG    MQTT       Publishing: emon/emontx3cm16/E2 0
2021-09-13 12:33:09,641 DEBUG    MQTT       Publishing: emon/emontx3cm16/E3 0
2021-09-13 12:33:09,643 DEBUG    MQTT       Publishing: emon/emontx3cm16/E4 0
2021-09-13 12:33:09,644 DEBUG    MQTT       Publishing: emon/emontx3cm16/T1 0
2021-09-13 12:33:09,645 DEBUG    MQTT       Publishing: emon/emontx3cm16/T2 0
2021-09-13 12:33:09,646 DEBUG    MQTT       Publishing: emon/emontx3cm16/T3 0
2021-09-13 12:33:09,648 DEBUG    MQTT       Publishing: emon/emontx3cm16/pulse 0
2021-09-13 12:33:09,649 DEBUG    MQTT       Publishing: emon/emontx3cm16/rssi -73
2021-09-13 12:33:09,650 INFO     MQTT       Publishing 'node' formatted msg
2021-09-13 12:33:09,651 DEBUG    MQTT       Publishing: emonhub/rx/16/values 0,0,10,0,0,0,0,0,0,0,0,0,0,0,-73
2021-09-13 12:33:09,759 DEBUG    MQTT       Publishing: emon/emontx3cm16/MSG 0
2021-09-13 12:33:09,760 DEBUG    MQTT       Publishing: emon/emontx3cm16/Vrms 0
2021-09-13 12:33:09,761 DEBUG    MQTT       Publishing: emon/emontx3cm16/P1 9
2021-09-13 12:33:09,763 DEBUG    MQTT       Publishing: emon/emontx3cm16/P2 0
2021-09-13 12:33:09,765 DEBUG    MQTT       Publishing: emon/emontx3cm16/P3 0
2021-09-13 12:33:09,766 DEBUG    MQTT       Publishing: emon/emontx3cm16/P4 0
2021-09-13 12:33:09,766 DEBUG    MQTT       Publishing: emon/emontx3cm16/E1 0
2021-09-13 12:33:09,767 DEBUG    MQTT       Publishing: emon/emontx3cm16/E2 0
2021-09-13 12:33:09,768 DEBUG    MQTT       Publishing: emon/emontx3cm16/E3 0
2021-09-13 12:33:09,769 DEBUG    MQTT       Publishing: emon/emontx3cm16/E4 0
2021-09-13 12:33:09,769 DEBUG    MQTT       Publishing: emon/emontx3cm16/T1 0
2021-09-13 12:33:09,770 DEBUG    MQTT       Publishing: emon/emontx3cm16/T2 0
2021-09-13 12:33:09,771 DEBUG    MQTT       Publishing: emon/emontx3cm16/T3 0
2021-09-13 12:33:09,773 DEBUG    MQTT       Publishing: emon/emontx3cm16/pulse 0
2021-09-13 12:33:09,774 DEBUG    MQTT       Publishing: emon/emontx3cm16/rssi -73
2021-09-13 12:33:09,774 INFO     MQTT       Publishing 'node' formatted msg
2021-09-13 12:33:09,775 DEBUG    MQTT       Publishing: emonhub/rx/16/values 0,0,9,0,0,0,0,0,0,0,0,0,0,0,-73
2021-09-13 12:33:09,998 DEBUG    MQTT       Publishing: emon/emontx3cm16/MSG 0
2021-09-13 12:33:09,999 DEBUG    MQTT       Publishing: emon/emontx3cm16/Vrms 0
2021-09-13 12:33:10,001 DEBUG    MQTT       Publishing: emon/emontx3cm16/P1 8
2021-09-13 12:33:10,002 DEBUG    MQTT       Publishing: emon/emontx3cm16/P2 0
2021-09-13 12:33:10,004 DEBUG    MQTT       Publishing: emon/emontx3cm16/P3 0
2021-09-13 12:33:10,005 DEBUG    MQTT       Publishing: emon/emontx3cm16/P4 0
2021-09-13 12:33:10,007 DEBUG    MQTT       Publishing: emon/emontx3cm16/E1 0
2021-09-13 12:33:10,008 DEBUG    MQTT       Publishing: emon/emontx3cm16/E2 0
2021-09-13 12:33:10,009 DEBUG    MQTT       Publishing: emon/emontx3cm16/E3 0
2021-09-13 12:33:10,011 DEBUG    MQTT       Publishing: emon/emontx3cm16/E4 0
2021-09-13 12:33:10,012 DEBUG    MQTT       Publishing: emon/emontx3cm16/T1 0
2021-09-13 12:33:10,014 DEBUG    MQTT       Publishing: emon/emontx3cm16/T2 0
2021-09-13 12:33:10,015 DEBUG    MQTT       Publishing: emon/emontx3cm16/T3 0
2021-09-13 12:33:10,017 DEBUG    MQTT       Publishing: emon/emontx3cm16/pulse 0
2021-09-13 12:33:10,018 DEBUG    MQTT       Publishing: emon/emontx3cm16/rssi -73
2021-09-13 12:33:10,019 INFO     MQTT       Publishing 'node' formatted msg
3

and emonhub output for the good emontx with only 9V AC connected (From Node : 15)
this one has values being sent correctly… and no 5V USB connected

2021-09-13 12:33:04,038 DEBUG    RFM2Pi     7566 Timestamp : 1631532784.034713
2021-09-13 12:33:04,039 DEBUG    RFM2Pi     7566 From Node : 15
2021-09-13 12:33:04,040 DEBUG    RFM2Pi     7566    Values : [979, 236.56, 1245, 3990, 20, -5, 3918, 5259, 28, 4294967292, 16.37, 300, 300, 0]
2021-09-13 12:33:04,040 DEBUG    RFM2Pi     7566      RSSI : -66
2021-09-13 12:33:04,041 DEBUG    RFM2Pi     7566 Sent to channel(start)' : ToEmonCMS
2021-09-13 12:33:04,041 DEBUG    RFM2Pi     7566 Sent to channel(end)' : ToEmonCMS
2021-09-13 12:33:04,116 DEBUG    MQTT       Publishing: emon/emontx3cm15/MSG 979
2021-09-13 12:33:04,118 DEBUG    MQTT       Publishing: emon/emontx3cm15/Vrms 236.56
2021-09-13 12:33:04,119 DEBUG    MQTT       Publishing: emon/emontx3cm15/P1 1245
2021-09-13 12:33:04,121 DEBUG    MQTT       Publishing: emon/emontx3cm15/P2 3990
2021-09-13 12:33:04,123 DEBUG    MQTT       Publishing: emon/emontx3cm15/P3 20
2021-09-13 12:33:04,124 DEBUG    MQTT       Publishing: emon/emontx3cm15/P4 -5
2021-09-13 12:33:04,125 DEBUG    MQTT       Publishing: emon/emontx3cm15/E1 3918
2021-09-13 12:33:04,127 DEBUG    MQTT       Publishing: emon/emontx3cm15/E2 5259
2021-09-13 12:33:04,128 DEBUG    MQTT       Publishing: emon/emontx3cm15/E3 28
2021-09-13 12:33:04,129 DEBUG    MQTT       Publishing: emon/emontx3cm15/E4 4294967292
2021-09-13 12:33:04,130 DEBUG    MQTT       Publishing: emon/emontx3cm15/T1 16.37
2021-09-13 12:33:04,132 DEBUG    MQTT       Publishing: emon/emontx3cm15/T2 300
2021-09-13 12:33:04,133 DEBUG    MQTT       Publishing: emon/emontx3cm15/T3 300
2021-09-13 12:33:04,134 DEBUG    MQTT       Publishing: emon/emontx3cm15/pulse 0
2021-09-13 12:33:04,136 DEBUG    MQTT       Publishing: emon/emontx3cm15/rssi -66
2021-09-13 12:33:04,137 INFO     MQTT       Publishing 'node' formatted msg
2021-09-13 12:33:04,137 DEBUG    MQTT       Publishing: emonhub/rx/15/values 979,236.56,1245,3990,20,-5,3918,5259,28,4294967292,16.37,300,300,0,-66
2021-09-13 12:33:08,488 DEBUG    RFM2Pi     7567 NEW FRAME : OK 5 0 0 0 0 0 0 167 79 219 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (-0)
2021-09-13 12:33:08,490 DEBUG    RFM2Pi     7567 Timestamp : 1631532788.487901
2021-09-13 12:33:08,491 DEBUG    RFM2Pi     7567 From Node : 5
2021-09-13 12:33:08,492 DEBUG    RFM2Pi     7567    Values : [0, 0, 0, 203.91, 21.900000000000002, 0, 0, 0, 0, 0, 0]
2021-09-13 12:33:08,492 DEBUG    RFM2Pi     7567 Sent to channel(start)' : ToEmonCMS
2021-09-13 12:33:08,493 DEBUG    RFM2Pi     7567 Sent to channel(end)' : ToEmonCMS
2021-09-13 12:33:08,684 DEBUG    MQTT       Publishing: emon/emonpi/power1 0
2021-09-13 12:33:08,685 DEBUG    MQTT       Publishing: emon/emonpi/power2 0
2021-09-13 12:33:08,686 DEBUG    MQTT       Publishing: emon/emonpi/power1pluspower2 0
2021-09-13 12:33:08,688 DEBUG    MQTT       Publishing: emon/emonpi/vrms 203.91
2021-09-13 12:33:08,689 DEBUG    MQTT       Publishing: emon/emonpi/t1 21.900000000000002
2021-09-13 12:33:08,690 DEBUG    MQTT       Publishing: emon/emonpi/t2 0
2021-09-13 12:33:08,691 DEBUG    MQTT       Publishing: emon/emonpi/t3 0
2021-09-13 12:33:08,693 DEBUG    MQTT       Publishing: emon/emonpi/t4 0
2021-09-13 12:33:08,694 DEBUG    MQTT       Publishing: emon/emonpi/t5 0
2021-09-13 12:33:08,696 DEBUG    MQTT       Publishing: emon/emonpi/t6 0
2021-09-13 12:33:08,697 DEBUG    MQTT       Publishing: emon/emonpi/pulsecount 0
2021-09-13 12:33:08,698 INFO     MQTT       Publishing 'node' formatted msg
2021-09-13 12:33:08,699 DEBUG    MQTT       Publishing: emonhub/rx/5/values 0,0,0,203.91,21.900000000000002,0,0,0,0,0,0
2021-09-13 12:33:09,308 DEBUG    RFM2Pi     7568 NEW FRAME : OK 16 85 85 85 85 85 85 95 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85
4

You have me totally confused there. The title of the topic is “Enontx will only transmit with USB 5V power connected” and you start off with

That seems to be saying contrary things, so tell me if I am correct here, because there’s no point in trying to diagnose a problem when the facts are unclear.

You have two emonTx’s, lets call them No. 15 & No.16, according to their NodeIDs.

No.15
This has a VCal of 298.22
This is the one that you say works as you expect, with only a nominal 9 V a.c. supply.
Post no.3 says it reports sensible values by radio to your emonPi.

No.16
This has a VCal of 268.97
This one you call “bad”. Post no.2 does show that it is transmitting - but what you have copied there is the factory test sequence. Not all values are zero - “P1” is used for a count-down. What we need to see is what happens after “P1” has counted down past zero.
Is that when

Does it give genuine data when powered at 5 V d.c.?

It looks to me as if either your a.c. adapter powering No.16 is not giving adequate voltage, or there’s a fault in the a.c. power supply department of the emonTx, or there’s too much current being drawn from the a.c. power. Have you connected anything (temperature sensors?) to this No.16 emonTx?

Can you measure the no-load voltage from both a.c. adapters? If you’re using the one we recommend for Australia, https://www.jaycar.com.au/9v-ac-1-amp-plugpack/p/MP3027, the no-load voltage is 10.4 V, the nominal voltage calibration constant is 300.0
Have you calibrated the emonTx’s? It looks to me as if you’ve only calibrated No.15., No.16 still has the UK default calibration.

5

Here is 15 and 16
Both have been on for over an hour
Both have only 9V AC connected
Both now have identical sketches and calibrations.

If i give 16 a 5V USB power supply and reset it starts to return values. Without 5V it stays at zero.

If P1 counting down… it’s still at “8”

image
image2688×1242 167 KB

image
image2688×1242 172 KB

6

Both AC power supplies are the jaycar variety.
I’ve tried switch power suppliers between each emontx… 15 always comes up fine. 16 is always zero unless it also has the 5V USB connected.

16 has been sitting a drawer for past 18 month waiting for this part of the project. So maybe I’m rusty and have forgotten something/config/switch

7

We know what the factory test does. What I need to know is how does it behave with the 5 V d.c. powering it? This would indirectly (knowing the calibration) tell me the voltage that the a.c. adapter is supplying.

Until proven otherwise, the a.c. adapter is the prime suspect.

8

There isn’t one that would give the symptoms you are describing. If you don’t have the jumper link (JP2) on the emonTx, there should be NO power at all - nothing should light up in the absence of the 5 V d.c. If the link is in place, and the emonTx has no external loads connected, and the a.c. adapter is good (it appears to be if it runs No.15 OK), then as I wrote earlier, it’s a problem with the a.c. power supply & regulator not providing enough power to run everything.

If you’ve swapped a.c. adapters, and you’ve no tools/instruments to measure inside the emonTx, it looks as if something has died in storage. If you can and want to investigate further, I can make suggestions as to what to check and measure. Otherwise, I suggest an email to the shop mentioning this topic.

[Edit]
The a.c. barrel connector isn’t corroded and giving a bad connection? Likewise JP2?

9

More testing.
I have 3 x antennas.
1 x emon Pi antenna
2 x emontx antennas.

One antenna I can put on either emontx, and that emontx works fine on AC power supply.

I can put any of the other two antennas on either emontx and the led just stays red.

Is there variation in the antennas the emontx do not like? All three antennas look cosmetically identical. No markings. There must be a difference in them that maybe needs the 5V USB to drive them?

10

I have confirmed JP2 is on each emontx
PCB’s and all connections are clean/shiny as new. No rust or corrosion anywhere.

11

The only explanation I’ve got is what I’ve already written - the a.c. voltage out of your Jaycar adapter, in combination with your mains voltage, is on the edge of the working range, and what looks to be antenna mismatch is drawing that additional bit of power that causes the voltage to collapse.

Maybe @Bill.Thomson can throw some light on this?

12

Which one of the two male connectors shown below,
do the connectors on the two antennas that don’t work, look like?
image

13

Photo of the whole antenna as provided by OEM when I purchased the emontx’s and emonpi. They are not aftermarket. And a photo of the connector on the antenna. It looks like SMA male to me.

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image1920×1695 197 KB

Also provided a photo of all 3 antennas. They all look identical to me. The middle one and bottom one look like they might be a bit grubby on the bottom. will give them a clean in some iso prop this evening and try again.

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image1920×3035 346 KB

And a photo of each of the AC power supply no load voltages

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For completeness, here are the female connectors for each emontx.

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And a dedicated general power outlet in consumer unit for 9V AC power adaptors (messy for now. Will tidy up with cable ties when this is all working). Fun fact - i never knew you could buy “extra wide” GPO sockets… the extra width between the sockets allows both power adaptors to be plugged in side by side. Nice.

image
image1920×2560 452 KB

14

Antenna connectors look OK. But rubber duck antennas typically aren’t as simple as they look.
You could have an open, or a low resistance DC connection that’s not “seen” at 433 MHz.
That’s another check you could make. Are the DC resistances of all three the same or nearly so?

Try inserting a piece of wire 164 mm long in the emonTx SMA jack and checking to see
if it makes the Tx behave the same as the two “bad” rubber duck antennas.

Solid or stranded doesn’t matter, although it’s usually a little easier to do this with solid vice stranded wire.

If your Tx is located within a few metres of your emonPi, there shouldn’t be any need to bend the wire.
i.e. straight out of the jack should work OK. However, if you don’t have the room, putting a 90° bend in
the end inserted in the SMA jack is OK too. (this is where solid wire has an advantage over stranded wire)

If the distance between the “transmitter” and “receiver” is fairly small, say less than 10 metres and there
are no RF obstructions in the path, (e.g. walls) then “it aint gotta be pretty, it just needs to work good enough
to do some troubleshooting with.”

BTW, NICE choice of meter. Many employers I’ve worked for over the last 45+ years (as do I) consider
the Fluke line of True RMS meters to be the “gold standard.”

15

That’s that theory gone out of the window - perhaps. I have an early V3.4 with the smaller reservoir capacitor on the a.c. supply, to which I’ve added another to bring it closer to the new value. That fails in much the same way at 8.5 V a.c. in. So I think there should be plenty of spare current at 10.5 V.

What’s puzzling me @Bill.Thomson, is the apparent link between the antenna and what appears to be the 3.3 V rail dropping out and causing a continual restart of the processor. The RFM69CW is by far the largest current consumer (about 30 mA transmitting at the standard +7 dBm and 45 mA at max power of +13 dBm - don’t try this with no antenna, vs 8 mA for the processor) but would a mismatch affect the current all that much, when the output is 6 dB below max?

16

That’s what made me think of a low DC resistance “connection” that’s not seen by the RF, but is
enough of an “overload” to make the power supply go nuts.

17

Hi, I’ve been lazy and continued using the emontx with 5v USB connected, as this makes them work reliably. I am now finding the time to get back into fixing the problem.

When testing the antennas with a meter to identify any differences that might be at play, what am I measuring? Should there be a resistance/ohms value when measuring between the antenna pin and the brass threaded sheath? I’ve had a go at that, and don’t get any useful readings. Typical 0 ohms.

I think next step I’ll pull the emontx out of the case, screw in the antenna and try taking readings of any solder pads where the sma female receiver is soldered to the pcb.

I have some solid copper wire on order (just a couple of meters) to see what that shows also (to poke directly in the female receiving bit.

I was contemplating soldering some wires onto a power rail somewhere. Is that a good testing step?. My meter has a record over time function (but only 20 samples a second). I was going to try and capture a voltage sag or similar to prove or disprove that being a problem. I don’t have a proper Oscope.

18

[Edit]

I’ve checked two (both 433 MHz version) and I read >60 MΩ on both. Given the form of the antenna, that’s what I would expect; however if you think about a folded dipole or a loop antenna, zero resistance at d.c. is reasonable.

Your first step will be to tack solder a piece of wire to replace the SMA antenna. It needs to be cut to the correct length of 175 mm (printed on the p.c.b.). I suspect that will do the trick.

If it doesn’t, then…
[/Edit]

install EagleCAD, download the PCB layout & circuit diagrams, and get those ‘working’. It’s a lot easier than looking at the printed versions. Second - the power rails come out at the screw connector, so that removes the need to solder wires on to monitor the power supply.

If Bill’s theory is correct, removing the SMA antenna and replacing it with a solid wire (and most of my emonTx’s never had the fixed antenna) will prove the problem one way or the other. I don’t advise trying to unsolder the SMA connector from the p.c.b. though.

19

The idea is to compare the readings you get from all three. Are they all the same or nearly so?
Or is one or two of them different from the third?

Like Robert, I read an “open” when I check the emonTx antenna I have.

If you do that, you’ll be reading the resistance of some of the electronic components in parallel
with the antenna. i.e. any reading you get doing it that way won’t be a true meaurement of the antenna’s DC resistance.

I’d avoid doing that. Too easy to damage the PC board and/or wind up with a cold joint unless
you know what you’re doing.

Inserting the wire directly into the SMA socket works quite well. If the wire fits in the socket loosely,
cut the wire a couple of millimeters longer and fold the end you insert in the socket, back on itself.