TED $20 Ebay

[Xringer]

I saw her post. It was about a receiver, not how the transmitter timing works..

But, I just looked the comments below her post, and found the Transmitter IC part number. (actually a transceiver).
It's the Home automation modem TDA5051A. It uses crystal clock in the 7mhz range for controlling the data I/O lines, (like any old tech modem).
And I assume it's micro controller is running TED firmware (which has a RTC running) is selecting the start packet time, once a second.

Without some knowledge of the micro controller, I'm pretty much where I started.

So, I'm going to assume the start time will be random, and not linked into the 60hz grid (which is a pretty good timebase).
And I'll assume the micro controller's clock is going to drift, in both transmitters (MTUs).

So, there will be clock frequency drift and that will cause signal interference.
I'm somewhat sure, because the time-of-day-clock on the LCD display has a long term error. (it's not using the 60hz grid for time keeping).

If they drift so the transmitters are interfering, that could cause the lost of hours of data..
So, I think circuit isolation will be needed.. Yikes it's almost 1AM..

~~~~

I wonder if they put a Listen-before-Transmit routine in the firmware??

[Xringer]

The box was a little beat up, so I wanted to do a quick check of the display unit.
I turned it on and entered the House Code for my existing TED.
My new TED display came right up showing the current power use, and the correct Date and Time!

Where did that come from?

It had to come from the MTU down in the breaker box, or the other display unit.
Either way, that unexpected time and date implies 2-way comms..

Or, the new TED has an unusually accurate clock, that just happened to be set to exact time of my old TED.. Back in 2008 or whenever..

[jeff5may]

Originally Posted by Xringer

Or, the new TED has an unusually accurate clock, that just happened to be set to exact time of my old TED.. Back in 2008 or whenever..

Nope, I highly doubt that. The new receiver obviously synced the time stamp with comms to and from the old unit. Upon entering your key code, the new receiver had to ping the old unit and ask for permission to listen. Somewhere during the process, a time stamp was gleaned and used for sync purposes.

[Xringer]

I found it a little strange. I figured the MTU down in the breaker box was just sending
the same old stuff over and over again, once per second.

From what I learned from the links posted by AC Hacker, some basic info being
transmitted by the MTU, and I don't think there's enough bytes to sneak in the full date and time..
Interfacing with The Energy Detective : scanlime

Byte 0: Header (always 0×55)
Byte 1: House code
Byte 2: Packet counter
Byte 3: Raw power, bits 7-0
Byte 4: Raw power, bits 15-8
Byte 5: Raw power, bits 23-16
Byte 6: Raw voltage, bits 7-0
Byte 7: Raw voltage, bits 15-8
Byte 8: Raw voltage, bits 23-16
Byte 9: Unknown (Flags?)
Byte 10: Checksum

If this is the data, then if the MTU (Measuring Transmitter Unit) is holding the Time & Date, buried it it's guts.
It must have received a request from the RDU that I had just put online.
Or, the T&D came from the other RDU.. (Remote Display Unit).
The RDU board has a Dallas RTC chip.

I didn't think these gizmos had 2-way comms.. I figured the transmitter
would send up the power & voltage data, and the receiver-display would be a receive-only unit..

[where2]

Reading the comments, instructions, and based on a vague knowledge I have of power line interface communications, I was just pondering what would happen if you took two MTU's and installed one MTU chatting on one phase, and attached the other MTU to talk down the other phase? Would it then be possible to run two TED's simultaneously for a setup like XRinger's where he's trying to measure two different sources?

Or alternatively, for use in a house like mine where I'd like to read what the house is using, and what the PV system is generating in real time. (without dropping $600 on a Brultech GEM)

[brogsie]

Set up my TED on New Years Day. Very easy to set up. Been monitoring my mini split.
This thing is great. Can't beat it for $20.
Thanks for the heads up Xringer.

[Xringer]

I'm just using mine as a down stairs monitor of the old TED (measured both Sanyos).
Maybe I'll hook up the current probes this week and measure them independently.

Glad I don't live in the mid west..
http://models.weatherbell.com/drudge_usa.png

[pinballlooking]

Originally Posted by brogsie

Set up my TED on New Years Day. Very easy to set up. Been monitoring my mini split.
This thing is great. Can't beat it for $20.
Thanks for the heads up Xringer.

I have mine sitting on the table I need to install it to monitor my Mini split. I agree you can’t beat 20 shipped.

[Xringer]

Got the new one hooked up for a little testing. It seems to be working.
I had to Zero out the history, so it would start fresh on the new one. (on right).



I'm not sure if these will keep working on the same circuit, but so far.. Okay..
I think the display updating might be a little slower than normal.. But not bad..

So far, the $20 TED is working as well as the $140 TED..

[pinballlooking]

Originally Posted by Xringer

I'm not sure if these will keep working on the same circuit, but so far.. Okay..
I think the display updating might be a little slower than normal.. But not bad..

So far, the $20 TED is working as well as the $140 TED..

When I called TED support they said just put each MTU on a different leg.
That way the will each have a path to talk on.