Rockwell Automation T8841 Trusted 8 Channel RTD FTA - Manual (Page 7)

Trusted
TM
RTD FTA T8841
Issue 6 Nov 07 PD-T8841 7
1. Description
Figure 2 shows a single channel of the RTD FTA. All eight channels are identical.
Figure 2 Single Channel Circuit
Each channel of the RTD FTA contains a precision RTD instrumentation amplifier circuit based on the
Burr Brown XTR105 device. The device is a monolithic 4-20mA, 2-wire current transmitter with two
precision current sources. It provides complete current excitation for Platinum RTD temperature
sensors and bridges, an instrumentation amplifier and current output circuits on a single integrated
circuit.
The amplifier gain can be configured for a wide range of temperature measurements. Total
unadjusted error of the complete current transmitter is low enough to permit use without adjustment in
many applications. This includes zero output current drift, span drift and non-linearity.
Each circuit contains configuration links allowing user selection of the following:
1. Input temperature measurement range.
2. Two and three wire input sensor operation.
3. Voltage output when appropriate links are fitted.
4. Amplifier gain.
5. Linear resistors.
6. Zero resistors.
The input temperature measurement range is individually configurable on each channel. The minimum
temperature setting for each of the two configurable ranges per channel can be factory pre-set over the
range -200
0 C to 800 0 C. The temperature measurement range for each of the two configurable ranges
per channel can be factory pre-set over the range 100 0 C to 1000 0 C.