Allen-Bradley MicroLogix 1200 User Manual page 31

2-Wire RTD Configuration
EXC 2
SENSE 2
RTN 2
NC
Using 2-wire configurations does not permit the
IMPORTANT
module to compensate for resistance error due to
lead wire length. The resulting analog data includes
the effect of this uncompensated lead wire resistance.
The module continues to place the uncompensated
analog data in the input data file, but the open-circuit
status bit (OCx) is set in word 4 of the input data file
for any enabled channel using a 2-wire configuration.
These status bits may be used in the control program
to indicate that the analog data includes error due to
uncompensated lead wires. See page 3-4 for a
detailed discussion of the open-circuit status bits.
3-Wire RTD Configuration
EXC 2
SENSE 2
RTN 2
NC
Installation and Wiring
Cable Shield (to Ground)
RTD EXC
Return
Belden 9501 Shielded Cable
Cable Shield (to Ground)
RTD EXC
Sense
Return
Belden 83503 or 9533 Shielded Cable
Publication 1762-UM003A-EN-P - February 2003
2-13
RTD EXC
Return
RTD EXC
Sense
Return