
2
Calibration
NOTE: Because the transmitter cannot output a negative current, the calibration of the zero
cannot be performed at 0 °C (0 mA). The zero calibration should be performed at 6 °C (.05 mA)
to ensure proper calibration of the transmitter. If the transmitter is calibrated at 0 °C, the output of
the transmitter may not be linear.
1. Select the desired temperature range by soldering the two designated pins together.
For 0 to 120 °C Solder jumper 1 to A
For 0 to 160 °C Solder jumper 2 to A
For 0 to 180 °C Solder jumper 3 to A
2. Connect a power supply of 24 VDC, a 1000Ωload resistor (decade box), and a digital
multimeter (4-½ digit minimum) as shown below. The load resistor should have an accuracy of
1000Ω+/- .1 Ω. If unsure of the decade box's accuracy, measure using the DMM. Other load
resistances can be used as long as the maximum of 1000Ωis not exceeded. The required
calibration voltage measured on the DMM is dependent on the value of Rload according to the
following formula: V(DMM) = Rload x Current (Ohm's Law)
3. Connect a resistance decade box with a resolution of at least .01 ohms to the input of the
transmitter. If unsure or concerned about the decade box's accuracy, measure the zero and span
resistance settings using a known-accurate ohmmeter and record decade box settings before
connecting decade box to the transmitter.
4. Set decade box resistance to simulate 6 °C (102.34 Ω).
5. Adjust ZERO potentiometer until the meter reads .05 volts (.05 volts x 1000 Ω= .05 mA).
6. Set decade box resistance to simulate the desired span temperature.
For 120 °C R = 146.061 Ω
For 160 °C R = 161.043 Ω
For 180 °C R = 168.478 Ω
7. Adjust SPAN potentiometer until the meter reads 1 volt (1 volt x 1000 Ω= 1 mA).
8. Repeat steps 4 - 7 until no further adjustment is necessary. The zero and span pots are non-
interacting so further adjustment should be minimal.