User Manual

Table Of Contents
On Air Message Format 3-1
SmartPoint Module for the Elster A3 Meter ECMTM40000
3 On Air Message Format
All fields are sent least-significant byte first.
The basic format of the on air message is as shown in the following table:
3.1 Field Definitions
3.1.1 Message Leader
This is a repeating stream of the value 0xAA used by the receiver to trip and synchronize to the
transmitted message. The leader is 152 bits or 19 bytes long.
3.1.2 Sync
8 bit Start of Message signal (0x36).
3.1.3 Meter ID Number
A unique identifier, different and fixed for each end point device, 28 bits long.
3.1.4 Customer ID
4 Bits of Customer ID.
Bytes
(Bits)
Field Description Value
0-18 Leader 0xAA
19 Sync Start of Msg 0x36
20-
23(0:3)
Meter ID
23(4:7) Customer ID 0x0
24 Control Control: 4 bits; Flags: 4 bits
25 Length 0x03 – 0xFF
26 Repeat Level/Sta-
tus
Repeat Level: 2 bits; Status: 6 bits
27 App Sequence
28 App Code
29-56 App Data 0-252 bytes, currently fixed at 28
bytes
57-60 CRC