Although it is best practice to make all your data available (e.g. as a table in an appendix), it is also important to summarize and describe your data for the reader, and to present your summaries in a table. The focus here is describing and summarizing the data from the dependent variable. As with graphs, the best approach for describing data depends on the data types.
Note that if you have an independent variable, and if it varied at all during the experiment despite being under your control (most instruments will vary a bit), it is important to plan to describe this also, though often this information is placed in an appendix. Since you'll be presenting your work as a poster, you should be prepared to answer questions about this, in case someone asks you.