I/O scanner for an industrial control

摘要

The I/O modules for an industrial control processor are connected together in a serial I/O ring. The processor performs an I/O scan sequence in which output data for the I/O modules is shifted serially from an output image table onto the I/O ring and input data from the I/O modules is pushed around the I/O ring and into the processor where it updates an input image table. Each I/O module can be configured to perform digital filtering and input pulse catching on the inputs and to enable a watchdog timer. Configuration data is sent out from the processor like output data and is latched into a configuration latch in the I/O module by a configure command from the processor.