Tex. Code Crim. Proc. art. 24.20
If the subpoena be returnable at some future date, the officer shall have authority to take bail of such witness for his appearance under said subpoena, which bond shall be returned with such subpoena, and shall be made payable to the State of Texas, in the amount in which the witness and his surety, if any, shall be bound and conditioned for the appearance of the witness at the time and before the court, magistrate or grand jury named in said subpoena, and shall be signed by the witness and his sureties. If the witness refuses to give bond, he shall be kept in custody until such time as he starts in obedience to said subpoena, when he shall be, upon affidavit being made, provided with funds necessary to appear in obedience to said subpoena.
Tex. Code Crim. Proc. § 24.20