Chapter 2: Modbus PLCs Using Modbus
21
The slave address (PLC ID#) is selected by connecting pins 24, 22, 18, 16, 14, 12, 10 and 8 to signal
ground at pin 26. A binary pattern is used, where zero bit = connect to pin 26 and a one bit = leave
unconnected. For example, the address 11 in binary is 00001011, which requires connection of pins
24, 22, 18, 16, and 12 to pin 26, as shown below.
Table 5 - Example for a Slave Address of 11
Specific modes of operation are selected by connecting pins 28 and 30 to signal ground at pin 26. The
following chart summarizes selection options where YES = connect to pin 26 and NO = leave
unconnected.
Table 6 - Mode Selection
The number of stop bits and parity are selected by connecting pins 17, 19, and 21 to signal ground at
pin 7. The following chart summarizes selection options where YES = connect to pin 7 and NO =
leave unconnected.
Table 8 - Stop Bit and Parity Selection