| 摘要 |
<p>An expansion module address method and apparatus for a Programmable Logic Controller (PLC) is taught. Briefly stated, a PLC base unit sends an address to an expansion module and modules attached thereto. Each expansion module takes the number it receives and considers it to be its own address number. Unless the number presented to it is a zero, the expansion module decrements the number and passes it onto the next module. Thereby each module knows its own address. Each expansion module has contained therein a plurality of address and data lines which are common to all modules with the exception of one address line which is interrupted by each module circuitry, which is used to decrement the address number and then passes it along the interrupted address line to the next module.</p> |
