Rockwell Automation 1771-IR Series D RTD Input Module User Manual - Manual (Page 12)

1–2 Overview of the RTD Input Module
Publication 1771Ć6.5.129 - March 2000
When using 10 ohm copper RTDs, you must dedicate your module
for exclusive use with 10 ohm copper RTDs. You can configure the
module to accept signals from any combination of 100 ohm platinum
and other types of non–copper RTDs. Both cases are determined by
block transfer write (BTW) selection.
The processor transfers data to and from the module using block
transfer write (BTW) and block transfer read (BTR) instructions in
your ladder diagram program. These instructions let the processor
obtain input values and status from the module, and let you establish
the module’s mode of operation (see below).
1. The processor transfers your configuration data and calibration
values to the module using a block transfer write instruction.
2. External devices generate analog signals that are transmitted to
the module.
Communication Between Processor and Module
Memory
User Program
To Output Devices
PC Processor
(PLC-5/40 Shown)
RTD Input Module
1771-IR Series B
BTW 1
BTR 4
5
6
2
3
12933-I
18
16
14
12
10
8
6
4
2
RTD
3. The module converts analog signals into binary or BCD format,
and stores theses values until the processor requests their
transfer.
4. When instructed by your ladder program, the processor performs
a read block transfer of the values and stores them in a data table.
How Analog Modules
Communicate with
Programmable Controllers