Signametrics Corporation SMU2060, Руководство оператора

Страница: 59 / 182

Figure 4-22. A DMM two-way handshake with a component handler requires current boos due to
handler’s high current requirements, to drive its optically-insolated input.
Figure 4-23. Two DMM two way handshake interface.
4.18 Measuring Thermocouples’ Temperature
59
Signametrics
The SMU2060 series of Digital Multimeters have built in linearization for eight thermocouple types
including B, E, J, K, N, R, S and T. In addition the DMM has means for both, entering and measuring the
reference (cold) junction temperature. The
DMMSetTemperatureUnits() selects between
o
C and
o
F.
Once selected, all subsequent temperature functions should consider the set temperature units.
DMMSetTCType() selects the type of thermocouple being measured. It can be used as frequently as
needed when measuring several types. Prior to measuring a Thermocouple it is important to set the
reference, or cold junction temperature. This can be done as often as necessary as to keep track of
variations in this temperature. Once set, all subsequent thermocouple measurements will use and
compensate for this temperature. One way to set this temperature is to simply pass it to the DMM using
the
DMMSetCJTemp() . Make sure to set it to the currently set temperature units. The cold junction
temperature range is 0
o
C to 50
o
C. If using the SM4042 or SM4040 to multiplex the thermocouples, and
the SM40T screw terminal block is being utilized to connect the thermocouples, DMMReadCJTemp()
should be used to measure the cold junction. Make sure to select and connect the “D” to the “A” bus of
the SM4000 switching. The third method of measuring and entering the cold junction temperature is by
measuring a user provided sensor. Provided this sensor have an output between –3.3V and +3.3V, and it