Freshness Counter

Freshness Counter Generation

It is possible to set up a Freshness Counter (FC) in a BC message (channel 4) or a user message (channels 5–132), provided that the message has a length greater than 3 bytes.

An FC field is incremented each time it is transmitted on the bus, and its initial value is 0.

Reserved fields where an FC will not work:

1. In all cases, an FC will not work when set within bits 0 to 7 of the first word (address) or in the last word (CRC).
2. In a BC status message, an FC will not work when set within bits 8 to 11 of the second word (reserved for BC ID and priority) .
3. In a frame control message, an FC will not work when set within bits 13 and 14 of the first word (reserved for BC ID).
4. In a user data, an FC will not work when set within word reserved for data checksum or CRC.

If an FC is set in one of those reserved areas, it will simply be overwritten by the current value of that area.

The FC is enabled or disabled for an address using the mxfASCBMsgFreshnessCounterSet() function. The current FC configuration can be obtained with mxfASCBMsgFreshnessCounterGet().

Freshness Counter Verification

To enable the Freshness Counter verification, call the mxfASCBMsgFreshnessCounterSet() function with the channel handle of the BM. This will enable the freshness counter verification on the BM for this specific user address.