Schneider Electric 890USE17700 User Manual
Page 117
Data Exchange
890USE17700 April 2004
117
Data and Status
Objects
Data exchange between the island and the fieldbus master involves three object
types:
z
data objects, which are operating values that the master either reads from the
input modules or writes to the output modules
z
status objects, which are module health records sent to the input area of the
process image by all of the I/O modules and read by the master
z
echo output data objects, which the digital output modules send to the input
process image; these objects are usually a copy of the data objects, but they can
contain useful information if a digital output channel is configured to handle the
result of a reflex action.