The beacon-enabled mode is effective in improving real-time performance of wireless sensor networks (WSNs). Keeping cluster heads and members synchronised in cluster-tree networks becomes challenging in presence of beacon collisions. In this paper, we study a collision-free multichannel superframe scheduling problem. We first formulate this problem in the satisfiability modulo theories (SMT) specification. It can be solved by an SMT solver but with limited scalability. Then, we present two more efficient approaches. Our results show that the proposed approaches can significantly improve the schedulability of superframes compared to the existing approach. Finally, we implement a real system based on a wireless network for industrial automation-process automation (WIA-PA) network to show the feasibility of our proposal.