Unitronics Uni-I/O UIS-WCB1 Installation Manual page 9

Wiring the Temperature Inputs
 Each input offers three modes: thermocouple, mV or RTD. You can set each input
N
OTE
independently. The mode is determined both by wiring and by the hardware
configuration within the software application.
In order to maintain correct operation of the temperature inputs, connect together points
RTn+ and RTn- of unused temperature inputs and leave point Rn+ unconnected (n
designates input number).
Thermocouple and mV
 When using thermocouple or mV modes, leave point Rn+ unconnected (n
N
OTE
designates input number).
Thermocouple
About thermocouple isolation
Although the temperature inputs are isolated from the bus and the module's power-supply
port, they are neither isolated from each other nor from the analog inputs. Therefore,
temperature inputs isolation may be bypassed when using an exposed-junction (non-
isolated) thermocouple in conjunction with analog inputs or another exposed-junction
thermocouple, which can lead to flow of unwanted currents through the thermocouple
wires that might interfere with thermocouple voltage reading.
In order to maintain temperature inputs isolation when using one or more of the analog
inputs or when using more than one thermocouple, either:
 Use isolated-junction thermocouples, or, if you are not using the analog inputs, you may
use up to one exposed-junction thermocouple per UIS-WCB1 module;
 Electrically isolate exposed-junction thermocouples from other electrically-conductive
parts of the system.
RTD
 When connecting 3- or 4-wire RTDs, make sure to use conductors of the same
N
OTE
type, width, and length for all RTD wires, otherwise module accuracy will degrade.
 When connecting 4-wire RTDs, use 3-wire cable and leave the unused wire
unconnected with minimal length.
Unitronics
Uni-I/O™
mV
9