= M-Stream 2.0 =

* [[MStream_ChangeLog]]

M-Stream data has packet structure. Large packets may be split to fragments with same Fragment ID to fit in encapsulating frame.

M-Stream 2.0 defines M-Stream Header, Event Header and User Payload data objects. In fragmentation process, M-Stream Header is persistent and should be present in all fragments. Event Header should be present in first fragment only.


||<-32 rowclass="bits">M-Stream Header||
||<:>word #||<:>byte offset||<:>bits||<:>description||
||<:|4>0||<:|4>0||31:24||[[DeviceId|Device ID]]||
||23:18||Flags||
||17:16||Subtype||
||15:0||Fragment length||
||<:|2>1||<:|2>4||31:24||Fragment ID||
||23:0||Fragment offset (bytes)||

||<-3 rowclass="bits">Flags bits||
||bit||value||
||5||LF (last fragment)||
||4||ACK||
||3:0||reserved||

Fragment length is defined as number of bytes starting at offset 8. For M-Stream frame of size N 32-bit words, fragment length value is 4*(N-2).

== Subtype 0: Trigger and User Data ==

||<-32 rowclass="bits">M-Stream Header||
||<:>word #||<:>byte offset||<:>bits||<:>description||
||<:|4>0||<:|4>0||31:24||[[DeviceId|Device ID]]||
||23:18||Flags||
||17:16||Subtype (0)||
||15:0||Fragment length, 4*(N-2)||
||<:|2>1||<:|2>4||31:24||Fragment ID||
||23:0||Fragment offset (bytes)||
||<:>2||<:>8||31:0||Device serial number||
||<:|2>3||<:|2>12||31:24||User defined bits||
||23:0||Event number||
||<-32 rowclass="bits">M-Stream Subtype 0 Payload||
||<:>4||<:>16||31:0||Event timestamp, TAI seconds||
||<:|2>5||<:|2>20||31:2||Event timestamp, TAI nanoseconds||
||1:0||Event timestamp, TAI flags||
||<:>6||<:>24||31:0||<|3>User defined payload||
||<:-3>...||
||<:>N-1||<:>4*(N-1)||31:0||

TAI flags: 2 - timecode is valid, otherwise invalid.

== Subtype 1: User Data, Channel-Based Readout ==

||<-32 rowclass="bits">M-Stream Header||
||<:>word #||<:>byte offset||<:>bits||<:>description||
||<:|4>0||<:|4>0||31:24||[[DeviceId|Device ID]]||
||23:18||Flags||
||17:16||Subtype (1)||
||15:0||Fragment length, 4*(N-2)||
||<:|2>1||<:|2>4||31:24||Fragment ID||
||23:0||Fragment offset (bytes)||
||<:>2||<:>8||31:0||Device serial number||
||<:|2>3||<:|2>12||31:24||Channel number||
||23:0||Event number||
||<-32 rowclass="bits">M-Stream Subtype 1 Payload||
||<:>4||<:>16||31:0||<|3>User defined payload||
||<:-3>...||
||<:>N-1||<:>4*(N-1)||31:0||

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[[CategoryMlink|MLink]] [[CategoryMStream|MStream]] [[CategoryRawData|RawData]]