Unitronics UniStream USC-B5-TA32 User Manual page 13

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 ensure that the temperature inputs operate correctly, connect the points RTn+ and RTn- of
unused temperature inputs together. Note that 'n' designates input number).
Thermocouple and mV
Thermocouple
About Thermocouple Isolation
Although the temperature inputs are isolated from the bus and the controller'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;
▪ Electrically isolate exposed-junction thermocouples from other electrically-conductive parts of the
system.
Unitronics
UniStream
mV
® PLC
13