Hi György,
The ZStarOut block must be used in automatic mode and the block must be executed in a loop using the sync-in pin with a periodic clock (or a counter).
With "automatic mode" the block send all initialization packets and start to send the command to read back from the serial the accellerometer and other data.
With the other working modality the ZStarOut block send only the selected packet.
![Arrow :arrow:](./images/smilies/icon_arrow.gif)
The periodic schedulation trick is necessary because the Serial block support only one byte input and not one string input.
Most of the commands are longer than one byte so, for this commands, the ZStarOut block must be executed more than one single time periodically in order to send the command byte by byte (1 byte for each execution). If you send only one single byte command the periodic schedulation tricks is not required but in this case You can directly send the command to the serial block using one constant generator (as in your zstar1.eywx patch)
Feel free to make any other questions,
bye