Specifications

4-Wire: For 4-wire operation, connect the RTD as shown in the diagram. If
the RTD has heavy excitation wires, they should be connected to the +I and
-I terminals. For proper 4-wire operation, the RTD set-up bit must be set to
1 (see Set-Up (SU) command). A typical set-up for 4-wire operation would
be 31071182.
Figure C-2. 4-Wire RTD Configuration.
2-Wire: The 2-wire connection requires two jumpers on the connector (J1
& J2) as shown in the diagram. This connection provides no lead compen-
sation. The RTD set-up bit can be either 0 or 1 for this connection.
Figure C-3. 2-Wire RTD Configuration.
Start-Up: During normal operation, the RTD lead resistance is periodically
scanned and filtered by the D1400 module. This may result in large initial
errors if the RTD sensor is connected while the D1400 is powered up. To
avoid this error, the sensor should be wired to the connector before power
is applied. The error may also be eliminated by performing a Remote Reset
(RR) command.
Lead Resistance Overload: If the lead resistance exceeds 50Ω, the output
data is set to +99999.99.
Sensor Grounding: The sensor input is electrically isolated from the power
and communications inputs for common-mode voltages up to 500V. If the
sensor is to be grounded or shielded, the ground connection should be made
to the -I terminal.