rtd DM6210, User Manual

Page: 73 / 91

10-5
Unipolar Calibration
Two adjustments are made to calibrate the A/D converter for the unipolar range of 0 to +10 volts. One is
the offset adjustment, and the other is the full scale, or gain, adjustment. Trimpot TR4 is used to make the
offset adjustment, and trimpot TR1 is used for gain adjustment. This calibration procedure is performed with
the module set up for a 0 to +10 volt input range. Before making these adjustments, make sure that the
jumpers on P5 and P6 are set for this range.
Use analog input channel 1 (gain = 1) while calibrating the module. Connect your precision voltage
source to channel 1. Set the voltage source to +1.22070 millivolts, start a conversion, and read the resulting
data. Adjust trimpot TR4 until it flickers between the values listed in the table below. Next, set the voltage to
+9.49829 volts, and repeat the procedure, this time adjusting TR1 until the data flickers between the values in
the table.
Bipolar Calibration
Two adjustments are made to calibrate the A/D converter for the bipolar ranges of ±5 and ±10 volts. One
is the offset adjustment, and the other is the full scale, or gain, adjustment. Trimpot TR2 is used to make the
offset adjustment, and trimpot TR1 is used for gain adjustment. These adjustments are made with the module
set for a range of -5 to +5 volts. Before making these adjustments, make sure that the jumpers on P5 and P6
are set for this range.
Use analog input channel 1 (gain = 1) while calibrating the module. Connect your precision voltage
source to channel 1. Set the voltage source to -4.99878 volts, start a conversion, and read the resulting data.
Adjust trimpot TR2 until it flickers between the values listed in the table below. Next, set the voltage to
+4.99634 volts, and repeat the procedure, this time adjusting TR1 until the data flickers between the values in
the table.
Data Values for Calibrating Unipolar Range (0 to +10 volts)
Offset (TR4)
Input Voltage = +1.22070 mV
Converter Gain (TR1)
Input Voltage = +9.99634 V
A/D Converted Data
0000 0000 0000
0000 0000 0001
1111 1111 1110
1111 1111 1111
Data Values for Calibrating Bipolar Ranges (Using -5 to +5 volts)
Offset (TR2)
Input Voltage = -4.99878V
Converter Gain (TR1)
Input Voltage = +4.99634V
A/D Converted Data
0000 0000 0000
0000 0000 0001
1111 1111 1110
1111 1111 1111