Rockwell Automation 1794-ASB/E Remote I/O Adapter Module User Manual - Manual (Page 16)

1–2 Overview of FLEX I/O and your Remote I/O Adapter Module
Publication 1794ĆUM009D-EN-P - April 2004
Data transfer to and from the remote I/O adapter/power supply and
discrete I/O modules occurs every flexbus scan. This provides the
controller with updated data.
The remote I/O adapter/power supply transfers data to the analog I/O
module (block transfer write) and from the analog I/O module (block
transfer read) using BTW and BTR instructions in your ladder
diagram program. These instructions let the adapter obtain input
values and status from the I/O module, and let you send output
values to establish the module’s mode of operation. The
communication process is described in the following illustration.
ADAPTER
ACTIVE FAULT
LOCAL
FAULT
24VDC
POWER SUPPLY
RIO ADAPTER
1794ĆASB
AllenĆBradley
2
AllenĆBradley
INPUT 0 INPUT 2 INPUT 4 INPUT 6 INPUT 1 INPUT 3 INPUT 5 INPUT 7
I V I V I V I V I V I V I V I V
ANALOG INPUT
1794-IE8
1
The adapter transfers your configuration data
to the module using a BTW.
Flexbus
External devices transmit
analog signals to the module.
2
The module converts analog signals
into binary format and stores these
values until the adapter requests their
transfer.
3
Your ladder program instructs the
adapter to perform a BTR of the values
and stores them in a data table.
4
The adapter and module determine
that the transfer was made without error
and input values are within specified
range.
5
Your ladder program can use and/or move the data (if valid)
before it is written over by the transfer of new data in a
subsequent transfer.
6
Your ladder program performs BTWs to the module when you power
it up, and any time you wish to reconfigure the module.
7
PWR
How FLEX I/O Modules
Communicate with
Programmable Controllers