SENSUS WATER METER WIRING DIAGRAM UPDATE
SENSUS WATER METER WIRING DIAGRAM DRIVER
SENSUS WATER METER WIRING DIAGRAM PLUS
SENSUS WATER METER WIRING DIAGRAM SERIES

Maybe 0.26 sec of data out of the one second capture, but I can ignore the silent times. A nice stream of clock pulses on one line (black) and some kind of data on the other (red). Trying again with green as common, I got (what I think to be) a good capture. After some head-scratching, it looked like the wire IРІР‚в„ўd used for common (black РІР‚вЂњ duh) was in fact one of the clock or data lines. It triggered, and I looked at the data, but it didnРІР‚в„ўt make any sense at all. I set a trigger for lo-hi edge on one of the clock/data lines (I didnРІР‚в„ўt know which) and left it for a while. I connected the wire to my USBee SX logic analyzer (the first time IРІР‚в„ўve used it!) and set it for 1 M samples at 1 РћСs/sample (lowest number and lowest rate offered). That gave me a nice wire coming out with all 3 connections I could play with. Decoding the dataР”В«ack when I hoped to be really non-invasive (never disconnecting the original wires), I made up something with spring contacts to connect to the screw heads of the 3-wire interface. I suppose if I wanted to be very polite about that I could interrupt the data line to the R900 with a relay so it would only hear the data it expected.

SENSUS WATER METER WIRING DIAGRAM SERIES

One possibility would be to put a (probably Schottky) diode in series with both the R900РІР‚в„ўs clock output and mine, hoping the 0.3V lower voltage level on the clock line would still allow the encoder to respond reliably.Р”Р„nd then thereРІР‚в„ўs the interesting question of how the unsolicited data transitions caused by my clock pulses might affect the R900.

SENSUS WATER METER WIRING DIAGRAM DRIVER

Of course it would be very inappropriate to impose my clock pulses on to the R900РІР‚в„ўs clock driver output. I suspect, but havenРІР‚в„ўt tried yet, that if I inject a suitable series of clock pulses at times of my choosing (maybe every 10 or 15 minutes?) the encoder will respond to me just like it does to the R900. (Thus the quotes.) While IРІР‚в„ўd like to just be a non-invasive listener, IРІР‚в„ўd really like more granular data.

A little more detailР”Р‡rom the product information on the R900, while it sends a 900 MHz spread-spectrum RF burst with the РІР‚СљlatestРІР‚Сњ usage data every 14 seconds, it only polls the meter once an hour. Thus the reading is essentially guaranteed to be accurate. An interesting feature of this mechanism is that the polling device always gets the complete total usage reading РІР‚вЂњ not a delta. The encoder extracts enough power from the 5V logic level clock stream to allow it to reply on the data line with the current values of the odometer counters. While it might be possible to harvest a little energy from the water flow, I think the encoder has no internal power.Р”Р„pparently (my inference) the device at the other end of the cable (here, the R900 battery-powered transmitter) polls the encoder by sending a stream of clock pulses to it. The 3-wire interface is part of that encoder. That encoder, which can be replaced on the fly, contains the clear plastic head with 6-digit odometer style counter, a big hand with a calibrated dial for the least significant reading, and an uncalibrated double ended red РІР‚СљspinnerРІР‚Сњ that shows flows too small to be seen easily on the big hand. The water meter seems to be cleverly designed with a separate РІР‚СљencoderРІР‚Сњ unit magnetically coupled to whatever it is that actually moves with the water flow inside the meter body. I can see both the clocks and the data now I just need to decode the data so my home monitoring system can use it.

The meter responds by putting (usage) data on the data line, clearly clocked out by the clock pulses from the transmitter. The transmitter apparently polls the meter periodically by sending a string of clock pulses to it.

The 3-wire connection between the two seems to consist of common, data (from meter to transmitter), and clock/power (from transmitter to meter). I guess IРІР‚в„ўll have to try to eavesdrop on the data going from the meter to the transmitter. I sent a note to Greg at and asked if I could help with development of the R900 code, but whatРІР‚в„ўs left would involve crypto stuff I know nothing about. Unfortunately, while it can receive the transmissions from an R900, it canРІР‚в„ўt decode the data (yet). ThereРІР‚в„ўs a cool 900 MHz utility meter monitor tool mentioned in this Hackaday post.

SENSUS WATER METER WIRING DIAGRAM UPDATE

Decoding that one is described below see Update 9/13/17.

SENSUS WATER METER WIRING DIAGRAM PLUS

That meter has since been replaced with a Mach 10 using E-coder Plus protocol.

Great! IРІР‚в„ўd like that data for my home monitoring system. My water meter (with a Neptune T-10 encoder) is connected to an external RF transmitter (a Neptune R900) to allow drive-by meter readings.

Sensus water meter wiring diagram