Rockwell Automation Allen-Bradley 1794-IRT8K, User Manual

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Publication 1794-6.5.12 - September 2011
Overview of FLEX I/O and Your Thermocouple, RTD, and Millivolt Input Module
3
The FLEX I/O Module in a
Logix Control System
The FLEX I/O Thermocouple, RTD, and Millivolt modules are intelligent
modules that interface analog signals with Rockwell Automation
programmable controllers through a FLEX I/O adapter module.
The adapter transfers data to and from the module. These transfers allow:
• the adapter to obtain input or output values and status from the module
• the user to establish the mode of operation through a process called
configuration
The following illustration shows the flow of communication between the
adapter and the I/O module.
Typical Communication Between the Adapter and a Module
IN 0 IN 2 IN 4 IN 6 IN 1 IN 3 IN 5 IN 7
TC RTD INPUT 8 CHANNEL
3
1794-IRT8
PWR
F F F F F F F F
45316
The adapter transfers your configuration data.
FlexBus
External devices transmit
analog signals to the
module.
The module converts
analog signals into binary
format and stores these
values until the adapter
requests their transfer.
The adapter receives data
from the modules and stores
it in the data table.
The adapter module determines that the
transfer was made without error and
input values are within specified range.
Your ladder program can use and/or
move the data (if valid) before it is
overwritten by the transfer of new data
in a subsequent transfer.
1
4
5
6
2
3
New configuration data can be sent to
the module any time during operation.
7
1794-ACN15
1794-ACNR15
1794-ACNR15K
1794-ADN
1794-AENT
1794-APBDPV1
1794-ASB
1794-APB
Adapter
1794-AENT shown