The request instructions format of

The request instructions format of the master and return data format from station multiple slaves are shown as formula (1) and formula (2), where in the formula the baud rate is 9600 bits/s, one character frame is 10 bits (one start bit + 8 bits of data a + 1 stop bit), ignoring a few free bits between characters frames, The time passing one character can be calculated by the formula (1). It's about 1.42 ms. In this formulaˈB is the baud rate and N is the data number. The length of read and write instruction is 16 characters, and the time that the host sends a data is 22.72 ms[10]. The slave sends data instruction back after receiving the host instruction and time-delaying. The delay time is usually tens of milliseconds. This data is given by some instrument manufacturer, and can set within a certain range by user, and is fixed and not given by some instrument manufacturer. The delay time in this design is fixed. The time of return data can be calculated by the formula (2), where in the formula t is the delay time. If data formats returns from slaves are 20 characters, assuming that t is 20 ms, the T is 28.4 ms.