Schneider Electric 890USE17700 - Manual (Page 169)

Advanced Configuration Features
890USE17700 April 2004 169
Output Data
Read/Write
Capabilities The registers in the output data process image are read/write-capable.
You can read (i.e., monitor) the process image using an HMI panel or the Advantys
configuration software. The data content that you see when you monitor the output
data image registers is updated in near-real time.
The island’s fieldbus master also writes updated control data to the output data
process image.
Input Data and I/
O Status Process
Image The input data and I/O status block (registers 45392 through 49487) handles the
input data and I/O status process image. Every I/O module on the island bus has
information that needs to be stored in this block.
z Each digital input module reports data (the on/off status of its input channels) in
one register of input data and I/O status block, then reports its status (e.g., the
presence or absence of errors) in the next register.
z
Each analog input module uses four registers in the input data and I/O status
block. It represents the analog data for each channel in separate registers and
the status of each channel in separate registers. Analog data is usually
represented with 11- or 12-bit resolution in the IEC format; status in an analog
input channel is usually represented by a series of status bits that report the
presence or absence of an out-of-range value in a channel.
z
Each digital output module reports an echo of its output data to a register in the
input data and I/O status block. Echo output data registers are essentially copies
of the register values that appear in the output data process image. This data is
usually not of much interest, but it can be useful in the event that a digital output
channel has been configured for a reflex action. In this case, the fieldbus master
can see the bit value in the echo output data register even though the output
channel is being updated inside the island bus.
z
Each analog output module uses two registers in the input data and I/O status
block to report status. Status in an analog output channel is usually represented
by a series of status bits that report the presence or absence of an out-of-range
value in a channel. Analog output modules do not report data in this block.
A detailed view of how the registers in the input data and I/O status block are
implemented is shown in the process image example.