| 摘要 |
A communication interface involves a processor that communicates to expansion modules in order to read and write discrete input/output, analog input/output, intelligent module control, and expansion module status. The expansion modules can be application specific integrated circuits (ASIC), each having a state machine architecture that responds appropriately to the input/output expansion bus signals. The ASIC can include error detection using the first byte of messages from the controller. Thus, the ASIC detects when an erroneous message from the controller has been communicated and transmits a message to expansion modules that their output states not be changed in response to the message from the controller. |
