SCM+ — the same idea, more room
A wider frame for the same cumulative reading. It exists because Itron ran out of meter IDs, not because anyone wanted better data.
SCM+ is the extended version of SCM. It carries the same kind of information in a larger frame: longer meter IDs and more precision on the consumption value.
The reason it exists is mundane and worth knowing, because it sets expectations correctly: the original SCM ID field ran out of space. Decades of deployment across a continent exhausts a fixed-width identifier. SCM+ widens it. What it does not do is change the fundamental design — it is still an odometer reading, still unprompted, still unencrypted.
The plus in SCM+ is about capacity, not capability. If you were hoping the newer message type carries interval history or flow rate, it does not — that is IDM, and only electric meters send it. Everything under the SCM caveats about cumulative readings applies here unchanged.
Properties
| Property | Value |
|---|---|
| Band | 902–928 MHz |
| Utilities | Gas, water, electric |
| Interval | Every few seconds, unprompted |
| Payload style | Odometer — cumulative |
| Meter ID width | Wider than SCM |
| Encryption | None |
| Decoders | rtlamr, rtl_433 |
rtlamr -msgtype=scm+ -filterid=YOUR_METER_ID
Listen for both
The two message types coexist on the same band, and there is no reliable way to predict from the outside which one a given meter uses — it depends on when the meter was manufactured and which firmware the utility deployed. Newer installations skew toward SCM+, but old and new sit side by side in the same street.
So on a first survey, do not choose. Ask for both:
rtlamr -msgtype=scm,scm+ -filterid=
Some devices are provisioned to transmit both message types. When that happens you will see two IDs that track each other perfectly, and the natural conclusion — that you have found two meters — is wrong.
The check is the one that settles every ambiguity on this site: compare the consumption values against the physical dials on your own meter. Two IDs whose numbers both match your dials are one meter talking twice.
Next
Where this leads.