Conveyor Belt Controller Circuit Connections Operation. Connections as shown in circuit tab 1 two ports of 89C2051 P1 P3 controls entire system. Pins P1.0, P1.1, P1.2 are connected to fwd, stop and drop controls through buffers 7407. P1.5, P1.6 P1.7 drives 3 Figure 5 Typical slave circuit for intelligent conveyor belt sensor system The belt is stopped whenever there is a failure or malfunction of the slave sensor (shown in figure 5). Slave sensor failure, not a break or failure of the conveyor belt may cause the master intelligent sensor to stop the belt.