Measurement-computing CIO-EXP-GP Bedienungsanleitung PDF herunterladen (Seite 22)

Voltages which exceed the ±5V range are in bold italics in the table above. Table 5-5 shows the

temperature at which the reading is clipped (the maximum readable temperature for thermocouple types

at a given gain).

Table 5-5. Maximum Readable Temperatures with A/D on ±5V Range

548°C1,450°C1,450°C1,450°C1,450R

576°C1,450°C1,450°C1,450°C1,450S

80°C287°C660°C900°C900E

115°C350°C350°C350°C350T

121°C484°C1,232°C1,250°C1,250K

95°C366°C750 °C750°C750J

X1000X250X100X10

Max readable temp vs GainMax °CType

From these tables, you can determine that if you want to use a J-type thermocouple to make a reading of

700 degrees, the gain should be set at 100. This yields a resolution of 0.48 degrees C per bit.

5.5 Setting the Gain

Once you have determined the gain required for your application, set the gain of the CIO-EXP-GP using

the following guide.

Amplification for ALL channels (board output gain) is switch selectable (S17) for X1 or X2.5.

Input amplification for EACH CHANNEL is switch selectable (CH0 through CH7) for X1, X10, X100 or

X1000. A user-specified gain may be set by supplying a precision resistor at position RX### and setting

the “U” option on switch CH ## to ON.

5.5.1 Setting the Board Gain

10V

+5 COMP

X2.5

GND

0.5V

S17

REM

Output Gain Switch

There is a switch on DIP switch block S17 (Figure 5-5) labeled

X1 and X2.5. Sliding this switch down amplifies the output of

the multiplexers by 2.5. The factory default position (up) has a

gain of 1 (unity).

The X2.5 gain switch is useful in some thermocouple

measurements. If you desire a voltage gain of 2.5, 25 or 250, set

this switch down. Recommended gains for thermocouples are

between X10 and X200.

Figure 5-5. Output Gain Switch Location

The effect of this switch is multiplicative with respect to the individual channel gains. For example, if

you have set an input channel gain to X100 and the board output gain to X2.5, the signal is amplified by

250 before it reaches the A/D board.

5.5.2 Setting the Channel Gain

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