IMC CANSAS - Pt100 (RTD) - Measurement; IMC Thermo Connector

To Next Page

To Previous Page

Measurement modes 211

Note

Only one thermocouple characteristic curve can be selected at the same time for one module. So it is

only possible to measure thermocouples of similar type at the same time. Only at the CANSAS

modules SC16, SCI8, SCI16 and CI8 it is possible to select different thermocouple characteristic

curves at the same time.

The endings from the measurement ranges can drift about 1K from the device configuration.

5.1.6.2 Pt100 (RTD) - measurement

Aside from thermocouples, RTD (Pt100) units can be directly connected in 4-wire-configuration (Kelvin

connection). An additional reference current source feeds a chain of up to 4 sensors in series.

With the imc Thermo connector, the connection terminals are already wired in such a way that this

reference current loop is closed "automatically".

If fewer than 4 Pt100 units are connected, the current-loop must be completed by a wire jumper from

the "last" RTD to -I4.

If you dispense with the "support terminals" (±I1 to ±I4) provided in the imc Thermo connector for 4-wire

connection, a standard terminal connector or any DSUB-15 connector can be used. The "current loop"

must then be formed between +I1 (DSUB Pin 9) and -I4 (DSUB Pin 6).

5.1.6.3 imc Thermo connector

The imc Thermo connector ACC/DSUB-T4 contains a screw terminal block in a DSUB-15 connector

housing with a built-in temperature sensor (Pt1000) for cold junction compensation. This provides for

direct connection of thermocouples of any type, directly to the differential inputs (+IN and -IN) without

external compensation leads. That connector can also be used for voltage measurement.

The difficulty with thermocouple measurements are the "parasitic" thermocouples which inevitably form

where parts of the contacts made of different materials meet. The temperature sensor measures the

temperature at the connection terminal and compensates the corresponding "error"-voltage. Normally,

the connection to this compensation point (inside the device) is made by special compensation leads or

connectors made of material identical to the respective thermocouple type, in order not to create

additional (uncontrolled) parasitic thermocouples.

imc's system avoids the problem through the use of individual compensation sensors directly inside the

connector plug, thus offering an especially simple, flexible and cost-effective connection solution.

Other manuals for IMC CANSAS