X62 Block diagram 

Loop powered digital communication

De X62 is a loop powered multi-variable Hart transmitter. This means that several  process variables can be measured and communicated digitally to the host. The low current consumption and large power supply voltage range assure that multiple Hart transmitters can be powered over 1 cable and from 1 barrier.

Galvanic separation

The galvanic separation assured the best possible tolerance against  EMI while measuring voltages in the microvolt range. Also, local grounding is required for the capacitance sensor, as it is an integral part of  measurement principle. In this case the galvanic separation permits the use of multiple X62 on the same Hart bus, which is itself grounded at one point, preferable the Barrier. 

A/D conversion

A Smartec UTI (Universal Transducer Interface) provides a cost effective  A/D conversion in the range of -10mV ... + 50mV, with a resolution of 1uV. This allows it to support all thermocouples over a large temperature range. 

In combination with the current source resistance can be measured in 2-, 3-, of 4-wire configuration, using the same circuit. Optionally, by turning off the current source, possible parasitic thermocouple voltages in the cabling can be compensated (Offset Compensation mode). This allows the distance between  X62 en sensor RTD to be over 100 m.


De input multiplexer supports measuring 18 input voltages (sense) of sourcing current through the same 18 terminals (force). This allows 2-, 3-, of 4-wire resistance measurements. The following combination of resistance and voltage measurements are configurable:

  • up to 6 RTDs, 4-wire with 1 wire common 0.
  • up to 9 RTDs, 3-wire with individual sense wire and 1 wire common 0.
  • up to 18 RTDs, 2-wire with 1 wire common 0.
  • up to 16 thermocouples with 1 wire common 0 (internal class B Pt100 cold junction compensation).
  • up to 15 thermocouples with 1 wire common 0 (optional external class A Pt100 cold junction compensation).
  • up to 18 sensors met -10mV ... + 50mV output voltage with 1 wire common 0.
  • up to 6 RTD/thermocouple pairs, 3-wire with individual sense wire and 1 wire common 0.

Capacitance measurement

The built-in capacitance measurement has  3 inputs with a range up to 2 nF. 

The active guard technology allows parasitic cable capacitances of in total 25 nF while a measuring frequency of maximal 100 kHz minimizes the sensitivity to electrode contamination. To you this means a reliable measurement using up to 250 m coaxial cable.


The X62 is being developed in cooperation with Smartec BV. Availability is expected in Q1 2005 following the certification process and field trials. The X62 has been  on display at the Industrial Processing 2004 and on the Instrument 2004 fair in Utrecht, The Netherlands. If you are interested in cooperating in a field trials please don't hesitate to contact us.