XCP标准中，DAQ列表内的编号ODT是否必须按递增顺序传输？

Let's tackle your two questions about XCP ODT transmission order directly—these are common points of confusion when setting up DAQ configurations:

1. Do ODTs in an XCP DAQ list have to be transmitted in increasing numerical order? #

Short answer: No, the XCP standard does not mandate ODTs be transmitted in ascending number order.

The transmission sequence of ODTs within a DAQ list is defined during the DAQ configuration phase (via commands like SET_DAQ_LIST_MODE or ADD_ODT_TO_DAQ). You’re free to arrange ODTs in any order that makes sense for your application—for example, prioritizing time-critical ODTs by placing them earlier in the sequence. While many implementations default to ascending order for simplicity, this is a convention, not a requirement from the standard.

2. Does the XCP standard require ODTs in a numbered DAQ list to be transmitted in an ordered fashion? #

Yes, but with an important caveat: ODTs must be transmitted in a fixed, pre-configured order—but that order doesn’t have to match their numerical IDs.

The XCP standard enforces that once you define the sequence of ODTs for a DAQ list, the slave must consistently transmit them in that exact sequence every time the DAQ list is triggered. This ensures the master can reliably parse the incoming data. However, this sequence is entirely configurable—you could set it to ODT 3 → ODT 1 → ODT 2 if needed, as long as both master and slave agree on the order during setup.

内容的提问来源于stack exchange，提问作者Bob