Rockwell Automation 1769-IR6 Compact I/O 1769-IR6 RTD/Resistance Input Module - Manual (Page 11)

Rockwell Automation Publication 1769-UM005B-EN-P - March 2012 11
Chapter
1
Overview
This chapter describes the six-channel 1769-IR6 RTD/resistance Input
module and explains how the controller reads resistance temperature detector
(RTD) or direct resistance-initiated analog input data from the module.
Included is:
· a general description of hardware features
· an overview of module and system operation
· compatibility
General Description The 1769-IR6 module supports RTD and direct resistance signal measurement
applications that require up to six channels. The module digitally converts
analog data and then stores the converted data in its image table.
The module supports connections from any combination of up to six input
devices. Each channel is individually configurable via software for 2- or 3-wire
RTD or direct resistance input devices. Channels are compatible with 4-wire
sensors, but the fourth sense wire is not used. Two programmable excitation
current values (0.5mA and 1.0mA) are provided, to limit RTD self-heating.
When configured for RTD inputs, the module can convert the RTD readings
into linearized digital temperature readings in °C or °F. When configured for
resistance analog inputs, the module can convert voltages into linearized
resistance values in ohms. The module assumes that the direct resistance input
signal is linear prior to input to the module.
Each channel provides open-circuit (all wires), short-circuit (excitation and
return wires only), and over- and under-range detection and indication.
IMPORTANT The module accepts input from RTDs with up to 3 wires. If
your application requires a 4-wire RTD, one of the two lead
compensation wires is not used, and the RTD is treated like
a 3-wire sensor. The third wire provides lead wire
compensation. See Chapter 3,
Installation and Wiring , for
more information.