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~~ODT~~
Subchannel numbering: CH10 vs. TMATS
Some data types have subchannels and some of these have additional attributes that are described in TMATS. To map the TMATS attributes to the subchannel, subchannel numbers are used. Depending on the recorder vendor TMATS and CH10 might use different numbers to describe the same subchannel. This sometimes even deviates within vendors (possibly by recorder model / firmware). The data types where conflicts have been seen start their numbering with 0 in CH10 and with 0 or 1 in TMATS.
The table below shows all data types where subchannels exist and the lowest numbers in CH10 and TMATS
| Data type | Lowest CH10 subchannel number | Lowest TMATS subchannel number |
|---|---|---|
| Analog (0x21) | 1 (0 means 256) | TMATS does not explicitly state the subchannel numbers (see CR80 2.1) |
| Message (0x30) | 0 | 0 or 1 (R-x\MSCN-n-m) |
| ARINC 429 (0x38) | 0 | 0 or 1 (R-x\ASN-n-m) |
| UART (0x50) | 0 | 0 or 1 (R-x\USCN-n-m) |
| Ethernet (0x68) | 0 | 0 or 1 (R-x\ENBR-n-m) |
| CAN (0x78) | 0 | 0 or 1 (R-x\CBN-n-m) |
Note: Actual problems have been seen on ARINC 429, UART and Ethernet. Problems on Message and CAN data types are expected but not confirmed.